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 (568, 555, 585, 574, 582, 580, 570) 
  AND pfv.product_id IN (
    2021, 2017, 2016, 1275, 1271, 1267, 1264, 
    1262, 1258, 1229, 1226, 1150, 1145, 
    1101, 1099, 1094, 1092, 1088, 1053
  ) 
  AND pfv.lang_code = 'en'

Query time 0.01418

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "76.48"
    },
    "nested_loop": [
      {
        "table": {
          "table_name": "fvd",
          "access_type": "ALL",
          "possible_keys": [
            "PRIMARY"
          ],
          "rows_examined_per_scan": 480,
          "rows_produced_per_join": 48,
          "filtered": "10.00",
          "cost_info": {
            "read_cost": "47.31",
            "eval_cost": "4.80",
            "prefix_cost": "52.11",
            "data_read_per_join": "145K"
          },
          "used_columns": [
            "variant_id",
            "variant",
            "lang_code"
          ],
          "attached_condition": "(`wearethehelpful_scalesta_net`.`fvd`.`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": [
            "wearethehelpful_scalesta_net.fvd.variant_id"
          ],
          "rows_examined_per_scan": 1,
          "rows_produced_per_join": 7,
          "filtered": "15.62",
          "cost_info": {
            "read_cost": "12.00",
            "eval_cost": "0.75",
            "prefix_cost": "68.91",
            "data_read_per_join": "8K"
          },
          "used_columns": [
            "variant_id",
            "feature_id",
            "position"
          ],
          "attached_condition": "(`wearethehelpful_scalesta_net`.`fv`.`feature_id` in (568,555,585,574,582,580,570))"
        }
      },
      {
        "table": {
          "table_name": "pfv",
          "access_type": "ref",
          "possible_keys": [
            "PRIMARY",
            "fl",
            "variant_id",
            "lang_code",
            "product_id",
            "fpl",
            "idx_product_feature_variant_id"
          ],
          "key": "PRIMARY",
          "used_key_parts": [
            "feature_id"
          ],
          "key_length": "3",
          "ref": [
            "wearethehelpful_scalesta_net.fv.feature_id"
          ],
          "rows_examined_per_scan": 7,
          "rows_produced_per_join": 0,
          "filtered": "0.71",
          "using_index": true,
          "cost_info": {
            "read_cost": "2.33",
            "eval_cost": "0.04",
            "prefix_cost": "76.48",
            "data_read_per_join": "297"
          },
          "used_columns": [
            "feature_id",
            "product_id",
            "variant_id",
            "lang_code"
          ],
          "attached_condition": "((`wearethehelpful_scalesta_net`.`pfv`.`variant_id` = `wearethehelpful_scalesta_net`.`fvd`.`variant_id`) and (`wearethehelpful_scalesta_net`.`pfv`.`product_id` in (2021,2017,2016,1275,1271,1267,1264,1262,1258,1229,1226,1150,1145,1101,1099,1094,1092,1088,1053)) and (`wearethehelpful_scalesta_net`.`pfv`.`lang_code` = 'en'))"
        }
      }
    ]
  }
}