SELECT 
  product_id, 
  feature_id, 
  variant_id 
FROM 
  cscart_product_features_values 
WHERE 
  product_id IN (
    11106, 11107, 11105, 11104, 11103, 11102, 
    11101, 11100, 11099, 11098, 11097, 
    11096, 11095, 11094, 11093, 11092, 
    11091, 11090, 11089, 11110, 11109, 
    11108
  ) 
  AND feature_id IN (553, 624, 623) 
  AND lang_code = 'en'

Query time 0.00404

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "16.04"
    },
    "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": "idx_product_feature_variant_id",
      "used_key_parts": [
        "product_id",
        "feature_id",
        "lang_code"
      ],
      "key_length": "12",
      "rows_examined_per_scan": 69,
      "rows_produced_per_join": 69,
      "filtered": "100.00",
      "using_index": true,
      "cost_info": {
        "read_cost": "9.14",
        "eval_cost": "6.90",
        "prefix_cost": "16.04",
        "data_read_per_join": "53K"
      },
      "used_columns": [
        "feature_id",
        "product_id",
        "variant_id",
        "lang_code"
      ],
      "attached_condition": "((`gaseus`.`cscart_product_features_values`.`product_id` in (11106,11107,11105,11104,11103,11102,11101,11100,11099,11098,11097,11096,11095,11094,11093,11092,11091,11090,11089,11110,11109,11108)) and (`gaseus`.`cscart_product_features_values`.`feature_id` in (553,624,623)) and (`gaseus`.`cscart_product_features_values`.`lang_code` = 'en'))"
    }
  }
}

Result

product_id feature_id variant_id
11089 553 1324
11089 623 1975
11089 624 1803
11090 553 1324
11090 623 2082
11090 624 1803
11091 553 1324
11091 623 2092
11091 624 1803
11092 553 1324
11092 623 2083
11092 624 1803
11093 553 1324
11093 623 2084
11093 624 1803
11094 553 1324
11094 623 2085
11094 624 1803
11095 553 1324
11095 623 2086
11095 624 1803
11096 553 1324
11096 623 2087
11096 624 1803
11097 553 1324
11097 623 2088
11097 624 1803
11098 553 1324
11098 623 2089
11098 624 1803
11099 553 1324
11099 623 2093
11099 624 1803
11100 553 2197
11100 623 1975
11100 624 1803
11101 553 2197
11101 623 2082
11101 624 1803
11102 553 2197
11102 623 2092
11102 624 1803
11103 553 2197
11103 623 2083
11103 624 1803
11104 553 2197
11104 623 2084
11104 624 1803
11105 553 2197
11105 623 2085
11105 624 1803
11106 553 2197
11106 623 2086
11106 624 1803
11107 553 2197
11107 623 2087
11107 624 1803
11108 553 2197
11108 623 2088
11108 624 1803
11109 553 2197
11109 623 2089
11109 624 1803
11110 553 2197
11110 623 2093
11110 624 1803