Datos BLOB devueltos en MySQL usando AES_DECRYPT con cláusula ORDER

ACTUALIZADO CAST a CHAR

SELECT `posts`.*, CAST(AES_DECRYPT(`posts`.`body`,SHA2(CONCAT('prefix',`users`.`guid`,'suffix'),512)) AS CHAR) as 'realbody'
  FROM `posts` JOIN `users` 
    ON `posts`.`user` = `users`.`id`
 ORDER BY `posts`.`id` DESC

Salida de muestra:

 | ID | USER | ... | REALBODY |
 ---...------------------------
 |  2 |    2 | ... |   Post 2 |
 |  1 |    1 | ... |   Post 1 |

Aquí está SQLFiddle demostración