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 (
    64828, 64829, 64830, 64834, 64831, 64492, 
    64493, 64494, 64495, 64496, 64483, 
    64827, 64491, 64497, 64583, 64584, 
    64585, 64586, 64587, 64588, 64813
  )

Query time 0.00184

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "54.63"
    },
    "nested_loop": [
      {
        "table": {
          "table_name": "pfvd",
          "access_type": "range",
          "possible_keys": [
            "PRIMARY"
          ],
          "key": "PRIMARY",
          "used_key_parts": [
            "variant_id",
            "lang_code"
          ],
          "key_length": "9",
          "rows_examined_per_scan": 21,
          "rows_produced_per_join": 21,
          "filtered": "100.00",
          "cost_info": {
            "read_cost": "25.23",
            "eval_cost": "4.20",
            "prefix_cost": "29.43",
            "data_read_per_join": "94K"
          },
          "used_columns": [
            "variant_id",
            "variant",
            "lang_code"
          ],
          "attached_condition": "((`webmarco`.`pfvd`.`variant_id` in (64828,64829,64830,64834,64831,64492,64493,64494,64495,64496,64483,64827,64491,64497,64583,64584,64585,64586,64587,64588,64813)) and (`webmarco`.`pfvd`.`lang_code` = 'en'))"
        }
      },
      {
        "table": {
          "table_name": "pfv",
          "access_type": "eq_ref",
          "possible_keys": [
            "PRIMARY"
          ],
          "key": "PRIMARY",
          "used_key_parts": [
            "variant_id"
          ],
          "key_length": "3",
          "ref": [
            "webmarco.pfvd.variant_id"
          ],
          "rows_examined_per_scan": 1,
          "rows_produced_per_join": 21,
          "filtered": "100.00",
          "cost_info": {
            "read_cost": "21.00",
            "eval_cost": "4.20",
            "prefix_cost": "54.63",
            "data_read_per_join": "23K"
          },
          "used_columns": [
            "variant_id",
            "position"
          ]
        }
      }
    ]
  }
}