Making CURDATE() recognize current_time()

$current_time = current_time('mysql');

$querystr = "
SELECT * FROM {$wpdb->prefix}usermeta
WHERE meta_key='bday_unix'
AND DATE_ADD( 
    from_unixtime(meta_value), INTERVAL YEAR( '{$current_time}' ) 
    - YEAR( from_unixtime( meta_value ) ) YEAR 
)
BETWEEN '{$current_time}' AND DATE_ADD( '{$current_time}', INTERVAL 30 DAY )";

Should work, I think.