SELECT 
  cscart_product_descriptions.product_id, 
  cscart_product_descriptions.short_description, 
  IF(
    cscart_product_descriptions.short_description = '' 
    OR cscart_product_descriptions.short_description IS NULL, 
    cscart_product_descriptions.full_description, 
    ''
  ) AS full_description, 
  cscart_product_descriptions.unit_name 
FROM 
  cscart_product_descriptions 
WHERE 
  cscart_product_descriptions.product_id IN (
    423, 424, 455, 433, 495, 453, 468, 467, 
    418, 420, 421, 422, 406, 407, 437, 494, 
    454, 442, 426, 429, 428, 410, 438, 440, 
    443, 463, 460, 450, 446, 447, 476, 457, 
    482, 483, 472, 441, 405, 403, 485, 492, 
    479, 480, 413, 401, 449, 474, 473, 448
  ) 
  AND cscart_product_descriptions.lang_code = 'de'

Query time 0.00074

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "115.21"
    },
    "table": {
      "table_name": "cscart_product_descriptions",
      "access_type": "range",
      "possible_keys": [
        "PRIMARY",
        "product_id"
      ],
      "key": "PRIMARY",
      "used_key_parts": [
        "product_id",
        "lang_code"
      ],
      "key_length": "9",
      "rows_examined_per_scan": 48,
      "rows_produced_per_join": 48,
      "filtered": "100.00",
      "index_condition": "((`danishecarter_latest`.`cscart_product_descriptions`.`product_id` in (423,424,455,433,495,453,468,467,418,420,421,422,406,407,437,494,454,442,426,429,428,410,438,440,443,463,460,450,446,447,476,457,482,483,472,441,405,403,485,492,479,480,413,401,449,474,473,448)) and (`danishecarter_latest`.`cscart_product_descriptions`.`lang_code` = 'de'))",
      "cost_info": {
        "read_cost": "105.61",
        "eval_cost": "9.60",
        "prefix_cost": "115.21",
        "data_read_per_join": "219K"
      },
      "used_columns": [
        "product_id",
        "lang_code",
        "short_description",
        "full_description",
        "unit_name"
      ]
    }
  }
}