SELECT 
  pfv.variant_id, 
  pfv.position, 
  pfvd.variant 
FROM 
  cscart_product_feature_variants AS pfv 
  INNER JOIN cscart_product_feature_variant_descriptions AS pfvd ON pfv.variant_id = pfvd.variant_id 
  AND pfvd.lang_code = 'en' 
WHERE 
  pfv.variant_id IN (
    19936, 62197, 10351, 62198, 10348, 19150, 
    62089, 22358, 62090, 62102, 23655, 
    62092, 62091, 35363, 62061, 62059, 
    34106, 62058, 62114, 24760, 62113, 
    45042, 62094, 62095, 62096, 62093
  )

Query time 0.00076

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "19.82"
    },
    "nested_loop": [
      {
        "table": {
          "table_name": "pfv",
          "access_type": "range",
          "possible_keys": [
            "PRIMARY",
            "variant_feature_idx",
            "idx_var_feat_pos"
          ],
          "key": "idx_var_feat_pos",
          "used_key_parts": [
            "variant_id"
          ],
          "key_length": "3",
          "rows_examined_per_scan": 26,
          "rows_produced_per_join": 26,
          "filtered": "100.00",
          "using_index": true,
          "cost_info": {
            "read_cost": "3.07",
            "eval_cost": "2.60",
            "prefix_cost": "5.67",
            "data_read_per_join": "29K"
          },
          "used_columns": [
            "variant_id",
            "position"
          ],
          "attached_condition": "(`cscart_db`.`pfv`.`variant_id` in (19936,62197,10351,62198,10348,19150,62089,22358,62090,62102,23655,62092,62091,35363,62061,62059,34106,62058,62114,24760,62113,45042,62094,62095,62096,62093))"
        }
      },
      {
        "table": {
          "table_name": "pfvd",
          "access_type": "eq_ref",
          "possible_keys": [
            "PRIMARY"
          ],
          "key": "PRIMARY",
          "used_key_parts": [
            "variant_id",
            "lang_code"
          ],
          "key_length": "9",
          "ref": [
            "cscart_db.pfv.variant_id",
            "const"
          ],
          "rows_examined_per_scan": 1,
          "rows_produced_per_join": 26,
          "filtered": "100.00",
          "cost_info": {
            "read_cost": "11.55",
            "eval_cost": "2.60",
            "prefix_cost": "19.82",
            "data_read_per_join": "194K"
          },
          "used_columns": [
            "variant_id",
            "variant",
            "lang_code"
          ]
        }
      }
    ]
  }
}