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, 
  cscart_product_descriptions.unit_name 
FROM 
  cscart_product_descriptions 
WHERE 
  cscart_product_descriptions.product_id IN (
    428383, 409077, 440298, 450604, 455510, 
    402558, 401092, 442722, 442428, 417957, 
    432262, 452815, 431646, 439685, 440664, 
    451688, 410924, 423745, 420062, 434608, 
    446159, 429578, 425486, 423026
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00115

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost": 0.04252208,
    "nested_loop": [
      {
        "table": {
          "table_name": "cscart_product_descriptions",
          "access_type": "range",
          "possible_keys": ["PRIMARY", "product_id"],
          "key": "PRIMARY",
          "key_length": "9",
          "used_key_parts": ["product_id", "lang_code"],
          "loops": 1,
          "rows": 24,
          "cost": 0.04252208,
          "filtered": 100,
          "attached_condition": "cscart_product_descriptions.product_id in (428383,409077,440298,450604,455510,402558,401092,442722,442428,417957,432262,452815,431646,439685,440664,451688,410924,423745,420062,434608,446159,429578,425486,423026) and cscart_product_descriptions.lang_code = 'en'"
        }
      }
    ]
  }
}