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 (
    96869, 96870, 96871, 96872, 96873, 96874, 
    96875, 96876, 96877, 96878, 96879, 
    96880, 96881, 96882, 96883, 96884, 
    96885, 96886, 96887, 96888, 96889, 
    96890, 96891, 96892, 96893, 96894, 
    96895, 96896, 96897, 96898
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00057

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "16.80"
    },
    "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": 30,
      "rows_produced_per_join": 30,
      "filtered": "100.00",
      "cost_info": {
        "read_cost": "13.80",
        "eval_cost": "3.00",
        "prefix_cost": "16.80",
        "data_read_per_join": "114K"
      },
      "used_columns": [
        "product_id",
        "lang_code",
        "short_description",
        "full_description"
      ],
      "attached_condition": "((`nuie_scalesta_net`.`cscart_product_descriptions`.`product_id` in (96869,96870,96871,96872,96873,96874,96875,96876,96877,96878,96879,96880,96881,96882,96883,96884,96885,96886,96887,96888,96889,96890,96891,96892,96893,96894,96895,96896,96897,96898)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}