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 (
    1202, 1203, 1204, 1205, 1212, 1213, 1214, 
    1215, 1216, 1207, 1206, 1208, 1209, 
    1210, 1211, 1217, 1218
  )

Query time 0.00051

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "61.21"
    },
    "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": 17,
          "rows_produced_per_join": 17,
          "filtered": "100.00",
          "index_condition": "(`atulecarter_atul_demo1`.`pfv`.`variant_id` in (1202,1203,1204,1205,1212,1213,1214,1215,1216,1207,1206,1208,1209,1210,1211,1217,1218))",
          "cost_info": {
            "read_cost": "37.41",
            "eval_cost": "3.40",
            "prefix_cost": "40.81",
            "data_read_per_join": "19K"
          },
          "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": [
            "atulecarter_atul_demo1.pfv.variant_id",
            "const"
          ],
          "rows_examined_per_scan": 1,
          "rows_produced_per_join": 17,
          "filtered": "100.00",
          "cost_info": {
            "read_cost": "17.00",
            "eval_cost": "3.40",
            "prefix_cost": "61.21",
            "data_read_per_join": "51K"
          },
          "used_columns": [
            "variant_id",
            "variant",
            "lang_code"
          ]
        }
      }
    ]
  }
}