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 (
    85227, 85228, 85229, 85230, 85231, 85232, 
    85233, 85234, 85235, 85236, 85237, 
    85238, 85239, 85240, 85241, 85242, 
    85243, 85973, 85974, 85975, 85976, 
    85977, 85978, 85979, 85980, 85981
  )

Query time 0.00453

JSON explain

{
  "query_block": {
    "select_id": 1,
    "nested_loop": [
      {
        "table": {
          "table_name": "pfv",
          "access_type": "range",
          "possible_keys": ["PRIMARY"],
          "key": "PRIMARY",
          "key_length": "3",
          "used_key_parts": ["variant_id"],
          "rows": 26,
          "filtered": 100,
          "index_condition": "pfv.variant_id in (85227,85228,85229,85230,85231,85232,85233,85234,85235,85236,85237,85238,85239,85240,85241,85242,85243,85973,85974,85975,85976,85977,85978,85979,85980,85981)"
        }
      },
      {
        "table": {
          "table_name": "pfvd",
          "access_type": "eq_ref",
          "possible_keys": ["PRIMARY"],
          "key": "PRIMARY",
          "key_length": "9",
          "used_key_parts": ["variant_id", "lang_code"],
          "ref": ["dev_db.pfv.variant_id", "const"],
          "rows": 1,
          "filtered": 100,
          "index_condition": "pfvd.lang_code = 'en'"
        }
      }
    ]
  }
}