SELECT 
  pf.feature_id, 
  pf.company_id, 
  pf.feature_type, 
  pf.parent_id, 
  pf.display_on_product, 
  pf.display_on_catalog, 
  pf.display_on_header, 
  pf.categories_path, 
  pf.status, 
  pf.comparison, 
  pf.position, 
  pf.purpose, 
  pf.feature_style, 
  pf.filter_style, 
  pf.feature_code, 
  pfd.description, 
  pfd.lang_code, 
  pfd.prefix, 
  pfd.suffix, 
  pfd.full_description, 
  pfv.value, 
  pfv.variant_id, 
  pfv.value_int, 
  pfv.product_id 
FROM 
  cscart_product_features_values AS pfv 
  LEFT JOIN cscart_product_features AS pf ON pfv.feature_id = pf.feature_id 
  LEFT JOIN cscart_product_features_descriptions AS pfd ON pfd.feature_id = pf.feature_id 
  AND pfd.lang_code = 'en' 
WHERE 
  1 = 1 
  AND pfv.product_id IN (
    7494, 7495, 7498, 7499, 7504, 7505, 7526, 
    7527, 2219, 5227, 5226, 2217, 5225, 
    2218, 1525, 1524, 5817, 1523, 5818, 
    5819, 5238, 5240, 5237, 5239, 5241, 
    3732, 6449, 1543, 6448, 2864, 5242, 
    2863, 5243, 1517, 1520, 1518, 1519, 
    5224, 1541, 1537, 1540, 1544, 1545, 
    2735, 5244, 6322, 1521, 1522, 5223, 
    5220, 3729, 5221, 5222, 1538, 1539, 
    1542
  ) 
  AND pfv.lang_code = 'en' 
  AND pf.feature_code IN ('Brand', 'ISBN', 'GTIN', 'MPN')

Query time 0.00578

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "1805.03"
    },
    "nested_loop": [
      {
        "table": {
          "table_name": "pfv",
          "access_type": "range",
          "possible_keys": [
            "PRIMARY",
            "fl",
            "lang_code",
            "product_id",
            "fpl",
            "idx_product_feature_variant_id"
          ],
          "key": "idx_product_feature_variant_id",
          "used_key_parts": [
            "product_id"
          ],
          "key_length": "3",
          "rows_examined_per_scan": 2717,
          "rows_produced_per_join": 1159,
          "filtered": "42.69",
          "index_condition": "((`gaseus`.`pfv`.`product_id` in (7494,7495,7498,7499,7504,7505,7526,7527,2219,5227,5226,2217,5225,2218,1525,1524,5817,1523,5818,5819,5238,5240,5237,5239,5241,3732,6449,1543,6448,2864,5242,2863,5243,1517,1520,1518,1519,5224,1541,1537,1540,1544,1545,2735,5244,6322,1521,1522,5223,5220,3729,5221,5222,1538,1539,1542)) and (`gaseus`.`pfv`.`lang_code` = 'en'))",
          "cost_info": {
            "read_cost": "1120.67",
            "eval_cost": "115.99",
            "prefix_cost": "1236.66",
            "data_read_per_join": "897K"
          },
          "used_columns": [
            "feature_id",
            "product_id",
            "variant_id",
            "value",
            "value_int",
            "lang_code"
          ]
        }
      },
      {
        "table": {
          "table_name": "pf",
          "access_type": "eq_ref",
          "possible_keys": [
            "PRIMARY"
          ],
          "key": "PRIMARY",
          "used_key_parts": [
            "feature_id"
          ],
          "key_length": "3",
          "ref": [
            "gaseus.pfv.feature_id"
          ],
          "rows_examined_per_scan": 1,
          "rows_produced_per_join": 463,
          "filtered": "40.00",
          "cost_info": {
            "read_cost": "289.98",
            "eval_cost": "46.40",
            "prefix_cost": "1642.64",
            "data_read_per_join": "547K"
          },
          "used_columns": [
            "feature_id",
            "feature_code",
            "company_id",
            "purpose",
            "feature_style",
            "filter_style",
            "feature_type",
            "categories_path",
            "parent_id",
            "display_on_product",
            "display_on_catalog",
            "display_on_header",
            "status",
            "position",
            "comparison"
          ],
          "attached_condition": "(`gaseus`.`pf`.`feature_code` in ('Brand','ISBN','GTIN','MPN'))"
        }
      },
      {
        "table": {
          "table_name": "pfd",
          "access_type": "eq_ref",
          "possible_keys": [
            "PRIMARY"
          ],
          "key": "PRIMARY",
          "used_key_parts": [
            "feature_id",
            "lang_code"
          ],
          "key_length": "9",
          "ref": [
            "gaseus.pfv.feature_id",
            "const"
          ],
          "rows_examined_per_scan": 1,
          "rows_produced_per_join": 463,
          "filtered": "100.00",
          "cost_info": {
            "read_cost": "115.99",
            "eval_cost": "46.40",
            "prefix_cost": "1805.03",
            "data_read_per_join": "1M"
          },
          "used_columns": [
            "feature_id",
            "description",
            "full_description",
            "prefix",
            "suffix",
            "lang_code"
          ]
        }
      }
    ]
  }
}