If you use this custom meta box code: https://github.com/WebDevStudios/Custom-Metaboxes-and-Fields-for-WordPress then this gist may be useful. It allows you to use the page slug as a "show-on" filter.

cmb_page_id.php

<?php
/**
 * Use the page slug to filter the 'show-on' of a meta box
 * @author Pat Ramsey
 * @link https://gist.github.com/ramseyp/6227383
 *
 * @param bool $display
 * @param array $meta_box
 * @return bool display metabox
 */
add_filter( 'cmb_show_on', 'add_for_page_slug', 10, 2 );
// Add for Page Slug
function add_for_page_slug( $display, $meta_box ) {

  if ( 'page-slug' !== $meta_box['show_on']['key'] )
		return $display;

	// Get the current ID
	if( isset( $_GET['post'] ) ) $post_id = $_GET['post'];
	elseif( isset( $_POST['post_ID'] ) ) $post_id = $_POST['post_ID'];
	if( !( isset( $post_id ) || is_page() ) ) return false;

	// Get page slug
	$cur_page = get_post( $post_id );
	$page_slug = $cur_page->post_name;

	// If value isn't an array, turn it into one
	$meta_box['show_on']['value'] = !is_array( $meta_box['show_on']['value'] ) ? array( $meta_box['show_on']['value'] ) : $meta_box['show_on']['value'];

	// See if there's a match
	if( in_array( $page_slug, $meta_box['show_on']['value'] ) )
		return true;
	else
		return false;
}