You case get single post with slug without using the loop. Let's use the get_posts() function.
$my_slug = 'my_slug';
$args = array(
'name' => $my_slug,
'post_type' => 'post',
'post_status' => 'publish',
'numberposts' => 1
);
$my_posts = get_posts($args);
$my_single_post = $my_posts ? $my_posts[0] : null;