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 (
    1750, 1747, 1711, 585, 1749, 4271, 1756, 
    14982, 4272, 1745, 4939, 2128, 23481, 
    1748, 6467, 1751, 1742, 27370, 4268, 
    4267, 40802, 1752, 41616, 4941, 1758, 
    41226, 1744, 33721, 4303, 34678, 1753, 
    1743
  ) 
  AND cscart_product_descriptions.lang_code = 'vi'

Query time 0.05688

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": 32,
          "filtered": 100,
          "index_condition": "cscart_product_descriptions.product_id in (1750,1747,1711,585,1749,4271,1756,14982,4272,1745,4939,2128,23481,1748,6467,1751,1742,27370,4268,4267,40802,1752,41616,4941,1758,41226,1744,33721,4303,34678,1753,1743) and cscart_product_descriptions.lang_code = 'vi'"
        }
      }
    ]
  }
}