meta_today

$meta_query = array(
	'relation' => 'AND',
	array(
		'key'     => 'is_sent',
		'value'   => 'no',
		'compare' => '=',
		'type'    => 'CHAR',
	),
	array(
		'key'     => 'notification_scheduled_date',
		'value'   => 'now',
		'compare' => '<=',
		'type'    => 'DATE',
	),
);