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 (
    96043, 96044, 96045, 96046, 96047, 96048, 
    96049, 96050, 96051, 96052, 96053, 
    96054, 96055, 96056, 96057, 96058, 
    96059, 96060, 96061, 96062, 96063, 
    96064, 96065, 96066, 96067, 96068, 
    96069, 96070, 96071, 96072
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00087

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 (96043,96044,96045,96046,96047,96048,96049,96050,96051,96052,96053,96054,96055,96056,96057,96058,96059,96060,96061,96062,96063,96064,96065,96066,96067,96068,96069,96070,96071,96072)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}

Result

product_id short_description full_description
96043
96044
96045
96046
96047
96048
96049
96050
96051
96052
96053
96054
96055
96056
96057
96058
96059
96060
96061
96062
96063
96064
96065
96066
96067
96068
96069
96070
96071
96072