$args = array(
    \'post_type\'  => \'appointments\',
    \'meta_query\' => array(
        \'relationship\' => \'AND\',
        array(
            \'key\'   => \'location\',
            \'value\' => $place //set this somewhere
        ),
        array(
            \'key\'   => \'timestamp\',
            \'value\' => $time //set this somewhere
        )
    )
);
$posts = new WP_Query( $args );

您可以灵活地添加任何其他需要的内容，例如，post_status.