SELECT 
  pfv.variant_id, 
  pfv.position, 
  pfvd.variant 
FROM 
  cscart_product_feature_variants AS pfv 
  INNER JOIN cscart_product_feature_variant_descriptions AS pfvd ON pfv.variant_id = pfvd.variant_id 
  AND pfvd.lang_code = 'en' 
WHERE 
  pfv.variant_id IN (
    1502, 1503, 1504, 1505, 1499, 1506, 1507, 
    1508, 1509, 1510, 1511, 1512, 1513, 
    1515, 1516, 1206, 1498, 1524, 1218, 
    1525, 1526, 1238, 1527, 1528, 1529, 
    1531, 1532, 1533, 1205, 1534, 1535, 
    1214, 1536, 1537, 1207, 1539, 1542, 
    1543, 1544, 1545, 1546, 1547, 1548, 
    1549, 1550, 1239, 1551, 1556, 1557, 
    1562, 1563, 1208, 1568, 1569, 1570, 
    1571, 1572, 1573, 1574, 1575, 1576, 
    1213, 1215, 1604, 1605
  )

Query time 0.00198

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "68.26"
    },
    "nested_loop": [
      {
        "table": {
          "table_name": "pfv",
          "access_type": "range",
          "possible_keys": [
            "PRIMARY"
          ],
          "key": "PRIMARY",
          "used_key_parts": [
            "variant_id"
          ],
          "key_length": "3",
          "rows_examined_per_scan": 65,
          "rows_produced_per_join": 65,
          "filtered": "100.00",
          "index_condition": "(`dev_yourmart_co_bw`.`pfv`.`variant_id` in (1502,1503,1504,1505,1499,1506,1507,1508,1509,1510,1511,1512,1513,1515,1516,1206,1498,1524,1218,1525,1526,1238,1527,1528,1529,1531,1532,1533,1205,1534,1535,1214,1536,1537,1207,1539,1542,1543,1544,1545,1546,1547,1548,1549,1550,1239,1551,1556,1557,1562,1563,1208,1568,1569,1570,1571,1572,1573,1574,1575,1576,1213,1215,1604,1605))",
          "cost_info": {
            "read_cost": "39.01",
            "eval_cost": "6.50",
            "prefix_cost": "45.51",
            "data_read_per_join": "74K"
          },
          "used_columns": [
            "variant_id",
            "position"
          ]
        }
      },
      {
        "table": {
          "table_name": "pfvd",
          "access_type": "eq_ref",
          "possible_keys": [
            "PRIMARY"
          ],
          "key": "PRIMARY",
          "used_key_parts": [
            "variant_id",
            "lang_code"
          ],
          "key_length": "9",
          "ref": [
            "dev_yourmart_co_bw.pfv.variant_id",
            "const"
          ],
          "rows_examined_per_scan": 1,
          "rows_produced_per_join": 65,
          "filtered": "100.00",
          "cost_info": {
            "read_cost": "16.25",
            "eval_cost": "6.50",
            "prefix_cost": "68.26",
            "data_read_per_join": "196K"
          },
          "used_columns": [
            "variant_id",
            "variant",
            "lang_code"
          ]
        }
      }
    ]
  }
}