SELECT 
  cscart_product_feature_variant_descriptions.variant, 
  cscart_product_feature_variants.variant_id, 
  cscart_product_feature_variants.feature_id, 
  cscart_product_features_values.variant_id as selected, 
  cscart_product_features.feature_type, 
  cscart_seo_names.name as seo_name, 
  cscart_seo_names.path as seo_path 
FROM 
  cscart_product_feature_variants 
  LEFT JOIN cscart_product_feature_variant_descriptions ON cscart_product_feature_variant_descriptions.variant_id = cscart_product_feature_variants.variant_id 
  AND cscart_product_feature_variant_descriptions.lang_code = 'en' 
  INNER JOIN cscart_product_features_values ON cscart_product_features_values.variant_id = cscart_product_feature_variants.variant_id 
  AND cscart_product_features_values.lang_code = 'en' 
  AND cscart_product_features_values.product_id = 66521 
  LEFT JOIN cscart_product_features ON cscart_product_features.feature_id = cscart_product_feature_variants.feature_id 
  LEFT JOIN cscart_seo_names ON cscart_seo_names.object_id = cscart_product_feature_variants.variant_id 
  AND cscart_seo_names.type = 'e' 
  AND cscart_seo_names.dispatch = '' 
  AND cscart_seo_names.lang_code = 'en' 
WHERE 
  1 
  AND cscart_product_feature_variants.feature_id IN (62, 104, 65, 68, 63) 
GROUP BY 
  cscart_product_feature_variants.variant_id 
ORDER BY 
  cscart_product_feature_variants.position, 
  cscart_product_feature_variant_descriptions.variant

Query time 0.00406

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "11.95"
    },
    "ordering_operation": {
      "using_filesort": true,
      "grouping_operation": {
        "using_temporary_table": true,
        "using_filesort": false,
        "nested_loop": [
          {
            "table": {
              "table_name": "cscart_product_features_values",
              "access_type": "ref",
              "possible_keys": [
                "variant_id",
                "lang_code",
                "product_id",
                "idx_product_feature_variant_id"
              ],
              "key": "idx_product_feature_variant_id",
              "used_key_parts": [
                "product_id"
              ],
              "key_length": "3",
              "ref": [
                "const"
              ],
              "rows_examined_per_scan": 15,
              "rows_produced_per_join": 7,
              "filtered": "50.00",
              "using_index": true,
              "cost_info": {
                "read_cost": "0.62",
                "eval_cost": "0.75",
                "prefix_cost": "2.12",
                "data_read_per_join": "299"
              },
              "used_columns": [
                "feature_id",
                "product_id",
                "variant_id",
                "lang_code"
              ],
              "attached_condition": "(`cscart_db`.`cscart_product_features_values`.`lang_code` = 'en')"
            }
          },
          {
            "table": {
              "table_name": "cscart_product_feature_variants",
              "access_type": "eq_ref",
              "possible_keys": [
                "PRIMARY",
                "feature_id",
                "position",
                "variant_feature_idx",
                "idx_var_feat_pos"
              ],
              "key": "PRIMARY",
              "used_key_parts": [
                "variant_id"
              ],
              "key_length": "3",
              "ref": [
                "cscart_db.cscart_product_features_values.variant_id"
              ],
              "rows_examined_per_scan": 1,
              "rows_produced_per_join": 5,
              "filtered": "75.51",
              "cost_info": {
                "read_cost": "2.41",
                "eval_cost": "0.57",
                "prefix_cost": "5.29",
                "data_read_per_join": "6K"
              },
              "used_columns": [
                "variant_id",
                "feature_id",
                "position"
              ],
              "attached_condition": "(`cscart_db`.`cscart_product_feature_variants`.`feature_id` in (62,104,65,68,63))"
            }
          },
          {
            "table": {
              "table_name": "cscart_product_features",
              "access_type": "eq_ref",
              "possible_keys": [
                "PRIMARY"
              ],
              "key": "PRIMARY",
              "used_key_parts": [
                "feature_id"
              ],
              "key_length": "3",
              "ref": [
                "cscart_db.cscart_product_feature_variants.feature_id"
              ],
              "rows_examined_per_scan": 1,
              "rows_produced_per_join": 5,
              "filtered": "100.00",
              "cost_info": {
                "read_cost": "1.42",
                "eval_cost": "0.57",
                "prefix_cost": "7.27",
                "data_read_per_join": "2K"
              },
              "used_columns": [
                "feature_id",
                "feature_type"
              ]
            }
          },
          {
            "table": {
              "table_name": "cscart_seo_names",
              "access_type": "ref",
              "possible_keys": [
                "PRIMARY",
                "dispatch"
              ],
              "key": "PRIMARY",
              "used_key_parts": [
                "object_id",
                "type",
                "dispatch",
                "lang_code"
              ],
              "key_length": "206",
              "ref": [
                "cscart_db.cscart_product_features_values.variant_id",
                "const",
                "const",
                "const"
              ],
              "rows_examined_per_scan": 1,
              "rows_produced_per_join": 5,
              "filtered": "100.00",
              "cost_info": {
                "read_cost": "1.42",
                "eval_cost": "0.57",
                "prefix_cost": "9.25",
                "data_read_per_join": "9K"
              },
              "used_columns": [
                "name",
                "object_id",
                "type",
                "dispatch",
                "path",
                "lang_code"
              ]
            }
          },
          {
            "table": {
              "table_name": "cscart_product_feature_variant_descriptions",
              "access_type": "eq_ref",
              "possible_keys": [
                "PRIMARY"
              ],
              "key": "PRIMARY",
              "used_key_parts": [
                "variant_id",
                "lang_code"
              ],
              "key_length": "9",
              "ref": [
                "cscart_db.cscart_product_features_values.variant_id",
                "const"
              ],
              "rows_examined_per_scan": 1,
              "rows_produced_per_join": 5,
              "filtered": "100.00",
              "cost_info": {
                "read_cost": "2.14",
                "eval_cost": "0.57",
                "prefix_cost": "11.95",
                "data_read_per_join": "42K"
              },
              "used_columns": [
                "variant_id",
                "variant",
                "lang_code"
              ]
            }
          }
        ]
      }
    }
  }
}