wp_schedule_single_event Doesn’t Work

I’m testing wp_schedule_single_event function with this code
and it looks like it never trigger function do_this_in_an_hour()

Can anybody help please.

function do_this_in_an_hour() {

	mail("[email protected]",
	"test",
	"test",
	"From: [email protected]"
	);

}
add_action('my_new_event','do_this_in_an_hour');

//wp_clear_scheduled_hook('my_new_event');
wp_schedule_single_event(time()+10, 'my_new_event');

//counter
$cnt=wp_next_scheduled('my_new_event') - time();
echo $cnt;