SELECT 
  cscart_product_descriptions.product_id, 
  cscart_product_descriptions.product, 
  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 
FROM 
  cscart_product_descriptions 
WHERE 
  cscart_product_descriptions.product_id IN (
    6417, 6416, 5607, 5605, 5606, 5699, 5703, 
    5701, 5700, 5697, 5702, 5698, 7249, 
    7247, 7243, 7248, 7246, 7244, 7242, 
    7245, 6692, 6702, 6703, 6704, 6705, 
    6707, 6708, 6706, 5704, 1297, 1301, 
    1298, 1299, 1296, 1294, 1300, 1295, 
    3576, 3585, 3584, 3575, 7601, 7602, 
    6709, 3146, 3752, 3145, 5096
  ) 
  AND cscart_product_descriptions.lang_code = 'de'

Query time 0.00133

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "33.61"
    },
    "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": "((`dbggbern`.`cscart_product_descriptions`.`product_id` in (6417,6416,5607,5605,5606,5699,5703,5701,5700,5697,5702,5698,7249,7247,7243,7248,7246,7244,7242,7245,6692,6702,6703,6704,6705,6707,6708,6706,5704,1297,1301,1298,1299,1296,1294,1300,1295,3576,3585,3584,3575,7601,7602,6709,3146,3752,3145,5096)) and (`dbggbern`.`cscart_product_descriptions`.`lang_code` = 'de'))",
      "cost_info": {
        "read_cost": "28.81",
        "eval_cost": "4.80",
        "prefix_cost": "33.61",
        "data_read_per_join": "183K"
      },
      "used_columns": [
        "product_id",
        "lang_code",
        "product",
        "short_description",
        "full_description"
      ]
    }
  }
}