SELECT 
  pfv.feature_id, 
  pfv.product_id, 
  pfv.variant_id, 
  fv.position, 
  fvd.variant 
FROM 
  cscart_product_features_values AS pfv 
  INNER JOIN cscart_product_feature_variants AS fv ON pfv.feature_id = fv.feature_id 
  AND pfv.variant_id = fv.variant_id 
  INNER JOIN cscart_product_feature_variant_descriptions AS fvd ON pfv.variant_id = fvd.variant_id 
  AND fvd.lang_code = 'en' 
WHERE 
  pfv.feature_id IN (
    637, 636, 647, 646, 623, 622, 626, 553, 
    625, 624, 627, 628, 595
  ) 
  AND pfv.product_id IN (
    13176, 13162, 13169, 13232, 13225, 13190, 
    13183, 13239, 13204, 13197, 13246, 
    13218, 13211, 13253, 13124, 13125, 
    13126, 13098, 13105, 13112, 13118, 
    13064, 13071, 13078, 13085, 13091, 
    12956, 12958, 13014, 13028, 13040, 
    13052, 12960, 12974, 12988, 13000, 
    12926, 12942
  ) 
  AND pfv.lang_code = 'en'

Query time 0.01118

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "254.45"
    },
    "nested_loop": [
      {
        "table": {
          "table_name": "pfv",
          "access_type": "range",
          "possible_keys": [
            "PRIMARY",
            "fl",
            "variant_id",
            "lang_code",
            "product_id",
            "fpl",
            "idx_product_feature_variant_id"
          ],
          "key": "PRIMARY",
          "used_key_parts": [
            "feature_id",
            "product_id"
          ],
          "key_length": "6",
          "rows_examined_per_scan": 494,
          "rows_produced_per_join": 269,
          "filtered": "54.46",
          "using_index": true,
          "cost_info": {
            "read_cost": "82.92",
            "eval_cost": "26.91",
            "prefix_cost": "109.83",
            "data_read_per_join": "208K"
          },
          "used_columns": [
            "feature_id",
            "product_id",
            "variant_id",
            "lang_code"
          ],
          "attached_condition": "((`test2_gaseus`.`pfv`.`feature_id` in (637,636,647,646,623,622,626,553,625,624,627,628,595)) and (`test2_gaseus`.`pfv`.`product_id` in (13176,13162,13169,13232,13225,13190,13183,13239,13204,13197,13246,13218,13211,13253,13124,13125,13126,13098,13105,13112,13118,13064,13071,13078,13085,13091,12956,12958,13014,13028,13040,13052,12960,12974,12988,13000,12926,12942)) and (`test2_gaseus`.`pfv`.`lang_code` = 'en'))"
        }
      },
      {
        "table": {
          "table_name": "fv",
          "access_type": "eq_ref",
          "possible_keys": [
            "PRIMARY",
            "feature_id"
          ],
          "key": "PRIMARY",
          "used_key_parts": [
            "variant_id"
          ],
          "key_length": "3",
          "ref": [
            "test2_gaseus.pfv.variant_id"
          ],
          "rows_examined_per_scan": 1,
          "rows_produced_per_join": 144,
          "filtered": "53.58",
          "cost_info": {
            "read_cost": "67.26",
            "eval_cost": "14.42",
            "prefix_cost": "204.00",
            "data_read_per_join": "164K"
          },
          "used_columns": [
            "variant_id",
            "feature_id",
            "position"
          ],
          "attached_condition": "(`test2_gaseus`.`fv`.`feature_id` = `test2_gaseus`.`pfv`.`feature_id`)"
        }
      },
      {
        "table": {
          "table_name": "fvd",
          "access_type": "eq_ref",
          "possible_keys": [
            "PRIMARY"
          ],
          "key": "PRIMARY",
          "used_key_parts": [
            "variant_id",
            "lang_code"
          ],
          "key_length": "9",
          "ref": [
            "test2_gaseus.pfv.variant_id",
            "const"
          ],
          "rows_examined_per_scan": 1,
          "rows_produced_per_join": 144,
          "filtered": "100.00",
          "cost_info": {
            "read_cost": "36.04",
            "eval_cost": "14.42",
            "prefix_cost": "254.45",
            "data_read_per_join": "449K"
          },
          "used_columns": [
            "variant_id",
            "variant",
            "lang_code"
          ]
        }
      }
    ]
  }
}