MD5 to protect password is changing the hash

I have a code to protect the database password very basic. But to log in I'm always using the following:

$email = $post['email'];
$senha = md5($post['senha']);
return $this->model->Query('SELECT * FROM 
usuario WHERE email = ? AND senha = ? AND deletado = ? 
ORDER BY id ASC', array($email, $senha, 0));

Although md5 began to display behavior that it had not noticed before, it is constantly changing the hash in the login, something that had never happened before, perhaps for lack of observation.

How do I have the hash of the database hit according to the login hash?

Att.