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 (
    5095, 3147, 5094, 5097, 7732, 1522, 1683, 
    1685, 2447, 3554, 3552, 3553, 7603, 
    7604, 7605, 7606, 4059, 3865, 4054, 
    4058, 4052, 4056, 4053, 3870, 3872, 
    3871, 3873, 3862, 5512, 5513, 5511, 
    5514, 5359, 2958, 7024, 5863, 5862, 
    6860, 6859, 6856, 6761, 4591, 5781, 
    5714, 7427, 4969, 2626, 2627
  ) 
  AND cscart_product_descriptions.lang_code = 'de'

Query time 0.00074

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 (5095,3147,5094,5097,7732,1522,1683,1685,2447,3554,3552,3553,7603,7604,7605,7606,4059,3865,4054,4058,4052,4056,4053,3870,3872,3871,3873,3862,5512,5513,5511,5514,5359,2958,7024,5863,5862,6860,6859,6856,6761,4591,5781,5714,7427,4969,2626,2627)) 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"
      ]
    }
  }
}