edited query with %

$excluded_playlists_game_id = 4;

$query_args = array(
    'posts_per_page' => -1,
    'post_type'      => 'xxx',
    'meta_query'     => array(
        'key'     => 'psi_playlist_games_$_psi_playlist_item',
        'value'   => $excluded_playlists_game_id,
        'compare' => '!=',
    ),
);

function playlist_filter( $where ) {
    global $wpdb;
    $where = str_replace(
        "meta_key = 'sd_tour_schedule_$",
        "meta_key LIKE 'sd_tour_schedule_%",
        $wpdb->remove_placeholder_escape($where)
    );
    return $where;
}

add_filter( 'posts_where', 'playlist_filter' );
$posts = get_posts( $query_args );
remove_filter( 'posts_where', 'playlist_filter' );