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 (
    95896, 95897, 95898, 95899, 95900, 95901, 
    95902, 95903, 95904, 95905, 95906, 
    95907, 95908, 95909, 95910, 95911, 
    95912, 95913, 95914, 95915, 95916, 
    95917, 95918, 95919, 95920, 95921, 
    95922, 95923, 95924, 95945
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00082

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "13.52"
    },
    "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": "10.52",
        "eval_cost": "3.00",
        "prefix_cost": "13.52",
        "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 (95896,95897,95898,95899,95900,95901,95902,95903,95904,95905,95906,95907,95908,95909,95910,95911,95912,95913,95914,95915,95916,95917,95918,95919,95920,95921,95922,95923,95924,95945)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}

Result

product_id short_description full_description
95896
95897
95898
95899
95900
95901
95902
95903
95904
95905
95906
95907
95908
95909
95910
95911
95912
95913
95914
95915
95916
95917
95918
95919
95920
95921
95922
95923
95924
95945