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 (
    96692, 96694, 97015, 97016, 97017, 97022, 
    97023, 97024, 97025, 97026, 97027, 
    97028, 97029, 97030, 97031, 97032, 
    97033, 97039, 97040, 97045, 97046, 
    97083, 97219, 97220
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00060

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "13.44"
    },
    "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": 24,
      "rows_produced_per_join": 24,
      "filtered": "100.00",
      "cost_info": {
        "read_cost": "11.04",
        "eval_cost": "2.40",
        "prefix_cost": "13.44",
        "data_read_per_join": "91K"
      },
      "used_columns": [
        "product_id",
        "lang_code",
        "short_description",
        "full_description"
      ],
      "attached_condition": "((`nuie_scalesta_net`.`cscart_product_descriptions`.`product_id` in (96692,96694,97015,97016,97017,97022,97023,97024,97025,97026,97027,97028,97029,97030,97031,97032,97033,97039,97040,97045,97046,97083,97219,97220)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}

Result

product_id short_description full_description
96692
96694
97015
97016
97017
97022
97023
97024
97025
97026
97027
97028
97029
97030
97031
97032
97033
97039
97040
97045
97046
97083
97219
97220