SELECT 
  product_id, 
  feature_id, 
  variant_id 
FROM 
  cscart_product_features_values 
WHERE 
  product_id IN (
    13164, 13165, 13166, 13167, 13168, 13163, 
    13162
  ) 
  AND feature_id IN (
    636, 647, 646, 623, 622, 626, 553, 625, 
    624, 627, 628, 595, 637
  ) 
  AND lang_code = 'en'

Query time 0.00439

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "6.75"
    },
    "table": {
      "table_name": "cscart_product_features_values",
      "access_type": "range",
      "possible_keys": [
        "PRIMARY",
        "fl",
        "lang_code",
        "product_id",
        "fpl",
        "idx_product_feature_variant_id"
      ],
      "key": "PRIMARY",
      "used_key_parts": [
        "feature_id",
        "product_id",
        "variant_id",
        "lang_code"
      ],
      "key_length": "15",
      "rows_examined_per_scan": 16,
      "rows_produced_per_join": 16,
      "filtered": "100.00",
      "using_index_for_skip_scan": true,
      "cost_info": {
        "read_cost": "5.15",
        "eval_cost": "1.60",
        "prefix_cost": "6.75",
        "data_read_per_join": "12K"
      },
      "used_columns": [
        "feature_id",
        "product_id",
        "variant_id",
        "lang_code"
      ],
      "attached_condition": "((`test2_gaseus`.`cscart_product_features_values`.`product_id` in (13164,13165,13166,13167,13168,13163,13162)) and (`test2_gaseus`.`cscart_product_features_values`.`feature_id` in (636,647,646,623,622,626,553,625,624,627,628,595,637)) and (`test2_gaseus`.`cscart_product_features_values`.`lang_code` = 'en'))"
    }
  }
}

Result

product_id feature_id variant_id
13162 553 1973
13163 553 1973
13164 553 1973
13165 553 1973
13166 553 1973
13167 553 1973
13168 553 1973
13162 595 1904
13163 595 1905
13164 595 1789
13165 595 2499
13166 595 1787
13167 595 1900
13168 595 1899
13162 622 2497
13163 622 2497
13164 622 2497
13165 622 2497
13166 622 2497
13167 622 2497
13168 622 2497
13162 623 2541
13163 623 2541
13164 623 2541
13165 623 2541
13166 623 2541
13167 623 2541
13168 623 2541
13162 624 1803
13163 624 1803
13164 624 1803
13165 624 1803
13166 624 1803
13167 624 1803
13168 624 1803
13162 625 2122
13163 625 2122
13164 625 2122
13165 625 2122
13166 625 2122
13167 625 2122
13168 625 2122
13162 626 2043
13163 626 2043
13164 626 2043
13165 626 2043
13166 626 2043
13167 626 2043
13168 626 2043
13162 627 1659
13163 627 1659
13164 627 1659
13165 627 1659
13166 627 1659
13167 627 1659
13168 627 1659
13162 628 1660
13163 628 1660
13164 628 1660
13165 628 1660
13166 628 1660
13167 628 1660
13168 628 1660
13162 636 2348
13163 636 2348
13164 636 2348
13165 636 2348
13166 636 2348
13167 636 2348
13168 636 2348
13162 637 2345
13163 637 2345
13164 637 2345
13165 637 2345
13166 637 2345
13167 637 2345
13168 637 2345
13162 646 2370
13163 646 2370
13164 646 2370
13165 646 2370
13166 646 2370
13167 646 2370
13168 646 2370
13162 647 2374
13163 647 2374
13164 647 2374
13165 647 2374
13166 647 2374
13167 647 2374
13168 647 2374