PDO Exception if epoch date has more than 11 characters

Thank you very much for developing this module, it works great.
But when you save an expiration date too far in the future (now allowed until December 31, 2050) the following exception is thrown:

PDOException: SQLSTATE[22003]: Numeric value out of range: 1264 Out of range value for column 'expiration' at row 1: UPDATE {access_code} SET code=:db_update_placeholder_0, expiration=:db_update_placeholder_1 WHERE ( (uid = :db_condition_placeholder_0) ); Array ( [:db_update_placeholder_0] => 123456789 [:db_update_placeholder_1] => 2556140399 [:db_condition_placeholder_0] => 33 ) en access_code_user_update() (línea 201 de /var/www/vhosts/jfmaguire.es/httpdocs/biomedicinalmc/sites/all/modules/access_code/access_code.module).

On my site, I can save dates until 2037 without rising the exception.
I'm using PHP 5.3.23, MySQL 5.5.30 and Drupal 7.21.