I checked that in order to save rate to database using rate_save_vote($widget...

I checked that in order to save rate to database using rate_save_vote($widget, $content_type, $content_id, $value, $ahah = FALSE, $reset = FALSE), we need the unique token. You can check this in rate_vote_ahah(). I have updated the patch, token will also be passed to the callbacks that have registered to the eventBeforeRate event.