How to add add_meta_box to specific Page Template?

If your custom page template filename is foobar.php, you can use get_post_meta():

global $post;
if ( 'foobar.php' == get_post_meta( $post->ID, '_wp_page_template', true ) ) {
    // The current page has the foobar template assigned
    // do something
}

Personally, I like calling this inside my add_meta_boxes_page callback, and wrapping it around the add_meta_box() call itself.

function wpse82477_add_meta_boxes_page() {
    global $post;
    if ( 'foobar.php' == get_post_meta( $post->ID, '_wp_page_template', true ) ) {
        add_meta_box( $args );
    }
}
add_action( 'add_meta_boxes_page', 'wpse82477_add_meta_boxes_page' );

You’ll just need to instruct users to save the page after assigning the template, so that the meta box appears.