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 (
    1755, 1754, 1750, 1747, 1749, 1756, 1746, 
    1745, 1748, 1751, 1757, 1742, 1752, 
    1760, 1759, 1758, 1744, 1753, 1743, 
    1761, 1762
  ) 
  AND cscart_product_descriptions.lang_code = 'vi'

Query time 0.00588

JSON explain

{
  "query_block": {
    "select_id": 1,
    "nested_loop": [
      {
        "table": {
          "table_name": "cscart_product_descriptions",
          "access_type": "range",
          "possible_keys": ["PRIMARY", "product_id"],
          "key": "PRIMARY",
          "key_length": "11",
          "used_key_parts": ["product_id", "lang_code"],
          "rows": 21,
          "filtered": 100,
          "index_condition": "cscart_product_descriptions.product_id in (1755,1754,1750,1747,1749,1756,1746,1745,1748,1751,1757,1742,1752,1760,1759,1758,1744,1753,1743,1761,1762) and cscart_product_descriptions.lang_code = 'vi'"
        }
      }
    ]
  }
}