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 (
    1560, 1916, 1526, 1592, 1563, 1562, 2117, 
    3038, 1564, 1599, 4733, 1607, 1776, 
    1610, 4734, 4735, 4737, 4765, 4766, 
    4767, 4846, 4845, 4839, 4852, 4854, 
    4853, 5064, 5063, 2758, 1559, 1600
  )

Query time 0.00245

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "32.56"
    },
    "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": 31,
          "rows_produced_per_join": 31,
          "filtered": "100.00",
          "index_condition": "(`softwarepirmam_hewadelivard_cscart_4`.`pfv`.`variant_id` in (1560,1916,1526,1592,1563,1562,2117,3038,1564,1599,4733,1607,1776,1610,4734,4735,4737,4765,4766,4767,4846,4845,4839,4852,4854,4853,5064,5063,2758,1559,1600))",
          "cost_info": {
            "read_cost": "18.61",
            "eval_cost": "3.10",
            "prefix_cost": "21.71",
            "data_read_per_join": "35K"
          },
          "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": [
            "softwarepirmam_hewadelivard_cscart_4.pfv.variant_id",
            "const"
          ],
          "rows_examined_per_scan": 1,
          "rows_produced_per_join": 31,
          "filtered": "100.00",
          "cost_info": {
            "read_cost": "7.75",
            "eval_cost": "3.10",
            "prefix_cost": "32.56",
            "data_read_per_join": "93K"
          },
          "used_columns": [
            "variant_id",
            "variant",
            "lang_code"
          ]
        }
      }
    ]
  }
}