SELECT 
  product_id, 
  feature_id, 
  variant_id 
FROM 
  cscart_product_features_values 
WHERE 
  product_id IN (
    149042, 149050, 149051, 149052, 149053, 
    149054, 149055, 149056, 149057, 149058, 
    149059, 149060, 149061, 149062, 149063, 
    149064, 149065, 149066, 149067, 149068, 
    149069, 149070, 149071, 149072, 149073, 
    149074, 149075, 149076, 149077, 149078, 
    149079, 149080, 149081, 149082, 149083, 
    149084, 149085, 149086, 149087, 149088, 
    149089, 149090, 149091, 149092, 149093, 
    149094, 149095, 149096, 149097, 149098, 
    149099
  ) 
  AND feature_id IN (548, 549) 
  AND lang_code = 'en'

Query time 0.00814

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "42.07"
    },
    "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": "lang_code",
      "used_key_parts": [
        "lang_code",
        "feature_id",
        "product_id"
      ],
      "key_length": "12",
      "rows_examined_per_scan": 102,
      "rows_produced_per_join": 102,
      "filtered": "100.00",
      "using_index": true,
      "cost_info": {
        "read_cost": "21.67",
        "eval_cost": "20.40",
        "prefix_cost": "42.07",
        "data_read_per_join": "78K"
      },
      "used_columns": [
        "feature_id",
        "product_id",
        "variant_id",
        "lang_code"
      ],
      "attached_condition": "((`webmarco`.`cscart_product_features_values`.`product_id` in (149042,149050,149051,149052,149053,149054,149055,149056,149057,149058,149059,149060,149061,149062,149063,149064,149065,149066,149067,149068,149069,149070,149071,149072,149073,149074,149075,149076,149077,149078,149079,149080,149081,149082,149083,149084,149085,149086,149087,149088,149089,149090,149091,149092,149093,149094,149095,149096,149097,149098,149099)) and (`webmarco`.`cscart_product_features_values`.`feature_id` in (548,549)) and (`webmarco`.`cscart_product_features_values`.`lang_code` = 'en'))"
    }
  }
}