SELECT 
  products.product_id, 
  descr1.product as product, 
  products.kl_erp_inventory_id, 
  products.product_type, 
  products.parent_product_id, 
  products.master_product_offers_count, 
  products.master_product_id, 
  products.company_id, 
  products.kl_enable_qc, 
  products.kl_qc_amount 
FROM 
  cscart_products as products 
  LEFT JOIN cscart_product_descriptions as descr1 ON descr1.product_id = products.product_id 
  AND descr1.lang_code = 'en' 
  LEFT JOIN cscart_product_prices as prices ON prices.product_id = products.product_id 
  AND prices.lower_limit = 1 
  AND prices.usergroup_id IN (0) 
  INNER JOIN cscart_products_categories as products_categories USE INDEX (
    idx_products_categories_composite
  ) ON products_categories.product_id = products.product_id 
  INNER JOIN cscart_categories ON cscart_categories.category_id = products_categories.category_id 
WHERE 
  1 
  AND (
    (
      1 
      AND products.product_id IN (66490)
    )
  ) 
GROUP BY 
  products.product_id 
ORDER BY 
  NULL asc

Query time 0.00066

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "0.88"
    },
    "ordering_operation": {
      "using_filesort": false,
      "grouping_operation": {
        "using_filesort": false,
        "nested_loop": [
          {
            "table": {
              "table_name": "products",
              "access_type": "const",
              "possible_keys": [
                "PRIMARY",
                "idx_products_inventory"
              ],
              "key": "PRIMARY",
              "used_key_parts": [
                "product_id"
              ],
              "key_length": "3",
              "ref": [
                "const"
              ],
              "rows_examined_per_scan": 1,
              "rows_produced_per_join": 1,
              "filtered": "100.00",
              "cost_info": {
                "read_cost": "0.00",
                "eval_cost": "0.10",
                "prefix_cost": "0.00",
                "data_read_per_join": "5K"
              },
              "used_columns": [
                "product_id",
                "kl_erp_inventory_id",
                "product_type",
                "company_id",
                "kl_enable_qc",
                "kl_qc_amount",
                "parent_product_id",
                "master_product_id",
                "master_product_offers_count"
              ]
            }
          },
          {
            "table": {
              "table_name": "descr1",
              "access_type": "const",
              "possible_keys": [
                "PRIMARY",
                "product_id",
                "idx_product_desc_lang",
                "idx_product_name_search",
                "idx_product_desc_sort"
              ],
              "key": "PRIMARY",
              "used_key_parts": [
                "product_id",
                "lang_code"
              ],
              "key_length": "9",
              "ref": [
                "const",
                "const"
              ],
              "rows_examined_per_scan": 1,
              "rows_produced_per_join": 1,
              "filtered": "100.00",
              "cost_info": {
                "read_cost": "0.00",
                "eval_cost": "0.10",
                "prefix_cost": "0.00",
                "data_read_per_join": "4K"
              },
              "used_columns": [
                "product_id",
                "lang_code",
                "product"
              ]
            }
          },
          {
            "table": {
              "table_name": "prices",
              "access_type": "const",
              "possible_keys": [
                "usergroup",
                "product_id",
                "lower_limit",
                "usergroup_id",
                "idx_product_prices_usergroup_limit",
                "idx_prices_discount_lookup",
                "idx_prices_min_calc",
                "idx_prices_usergroup_lookup",
                "idx_prices_usergroup_product"
              ],
              "key": "usergroup",
              "used_key_parts": [
                "product_id",
                "usergroup_id",
                "lower_limit"
              ],
              "key_length": "9",
              "ref": [
                "const",
                "const",
                "const"
              ],
              "rows_examined_per_scan": 1,
              "rows_produced_per_join": 1,
              "filtered": "100.00",
              "using_index": true,
              "cost_info": {
                "read_cost": "0.00",
                "eval_cost": "0.10",
                "prefix_cost": "0.00",
                "data_read_per_join": "24"
              },
              "used_columns": [
                "product_id",
                "lower_limit",
                "usergroup_id"
              ]
            }
          },
          {
            "table": {
              "table_name": "products_categories",
              "access_type": "ref",
              "possible_keys": [
                "idx_products_categories_composite"
              ],
              "key": "idx_products_categories_composite",
              "used_key_parts": [
                "product_id"
              ],
              "key_length": "3",
              "ref": [
                "const"
              ],
              "rows_examined_per_scan": 1,
              "rows_produced_per_join": 1,
              "filtered": "100.00",
              "using_index": true,
              "cost_info": {
                "read_cost": "0.43",
                "eval_cost": "0.10",
                "prefix_cost": "0.53",
                "data_read_per_join": "16"
              },
              "used_columns": [
                "product_id",
                "category_id"
              ]
            }
          },
          {
            "table": {
              "table_name": "cscart_categories",
              "access_type": "eq_ref",
              "possible_keys": [
                "PRIMARY",
                "p_category_id"
              ],
              "key": "PRIMARY",
              "used_key_parts": [
                "category_id"
              ],
              "key_length": "3",
              "ref": [
                "cscart_db.products_categories.category_id"
              ],
              "rows_examined_per_scan": 1,
              "rows_produced_per_join": 1,
              "filtered": "100.00",
              "using_index": true,
              "cost_info": {
                "read_cost": "0.25",
                "eval_cost": "0.10",
                "prefix_cost": "0.88",
                "data_read_per_join": "2K"
              },
              "used_columns": [
                "category_id"
              ]
            }
          }
        ]
      }
    }
  }
}