Выполняет правило раньше времени

$usid = $_SESSION["user_id"];
 
$db->Query("SELECT * FROM ".$pref."_users_b WHERE id = '$usid' LIMIT 1");
$update = $db->FetchArray();
 
$update_time_a_t = $tank["time_a_t"]; // Дата окончания аренды.
$update_time_b_t = $tank["time_b_t"]; // Дата окончания аренды.
 
$time_update = time(); // Текущая дата.
 
if($update_time_a_t <= $time_update){
$db->Query("UPDATE ".$pref."_users_b SET a_t = '0', a_b = '0', last_sbor = '0', name_a_t = 'Танк M6', dohod_a_t = '30', price_a_t = '100', time_a_t = '0', next_name_a_t = 'Танк T29', next_dohod_a_t = '40', next_price_a_t = '500', next_img_a_t = 't29.png', next_time_a_t = '90',  lvl_a_t = '0' WHERE id = '$usid'");      
}
if($update_time_b_t <= $time_update){
$db->Query("UPDATE ".$pref."_users_b SET b_t = '0', a_b = '0', last_sbor_b = '0', name_b_t = 'Танк КВ 1С', doxod_b_t = '40', price_b_t = '120', time_b_t = '0', next_name_b_t = 'Танк КВ 85', next_doxod_b_t = '50', next_price_b_t = '600', next_img_b_t = '85.png', next_time_b_t = '80',  lvl_b_t = '0' WHERE id = '$usid'");               
}