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 (
    1324, 2002, 2092, 2099, 2083, 2100, 2085, 
    2101, 2087, 2088, 2197, 1975, 2082, 
    2084, 2086, 2089, 2093, 2094, 2095, 
    2096, 2090, 2170, 2158, 2159, 2160, 
    2155, 2156, 2157, 2171, 2228, 1803, 
    1659, 2229, 2227
  )

Query time 0.00053

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "35.71"
    },
    "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": 34,
          "rows_produced_per_join": 34,
          "filtered": "100.00",
          "index_condition": "(`gaseus`.`pfv`.`variant_id` in (1324,2002,2092,2099,2083,2100,2085,2101,2087,2088,2197,1975,2082,2084,2086,2089,2093,2094,2095,2096,2090,2170,2158,2159,2160,2155,2156,2157,2171,2228,1803,1659,2229,2227))",
          "cost_info": {
            "read_cost": "20.41",
            "eval_cost": "3.40",
            "prefix_cost": "23.81",
            "data_read_per_join": "38K"
          },
          "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": [
            "gaseus.pfv.variant_id",
            "const"
          ],
          "rows_examined_per_scan": 1,
          "rows_produced_per_join": 34,
          "filtered": "100.00",
          "cost_info": {
            "read_cost": "8.50",
            "eval_cost": "3.40",
            "prefix_cost": "35.71",
            "data_read_per_join": "105K"
          },
          "used_columns": [
            "variant_id",
            "variant",
            "lang_code"
          ]
        }
      }
    ]
  }
}