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 
FROM 
  cscart_product_descriptions 
WHERE 
  cscart_product_descriptions.product_id IN (
    90611, 90662, 90668, 90604, 90610, 90650, 
    90676, 90692, 90693, 90653, 90659, 
    90618, 90634, 90635, 90643, 90595, 
    90601, 90652, 90658, 90594, 90600, 
    90666, 90608, 84041, 84232, 84044, 
    84235, 90656, 84236, 90598, 84043, 
    84040, 84231, 84234, 88100, 87864, 
    87866, 84039, 84230, 84042, 88098, 
    84233, 87831, 87844, 87850, 88096, 
    87860, 87862
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00059

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "21.63"
    },
    "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",
      "cost_info": {
        "read_cost": "16.83",
        "eval_cost": "4.80",
        "prefix_cost": "21.63",
        "data_read_per_join": "183K"
      },
      "used_columns": [
        "product_id",
        "lang_code",
        "short_description",
        "full_description"
      ],
      "attached_condition": "((`nuie_scalesta_net`.`cscart_product_descriptions`.`product_id` in (90611,90662,90668,90604,90610,90650,90676,90692,90693,90653,90659,90618,90634,90635,90643,90595,90601,90652,90658,90594,90600,90666,90608,84041,84232,84044,84235,90656,84236,90598,84043,84040,84231,84234,88100,87864,87866,84039,84230,84042,88098,84233,87831,87844,87850,88096,87860,87862)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}