wp_check_post_lock()

wp_check_post_lock( int|WP_Post $post ): int|false

function wp_check_post_lock( $post ) {
	$post = get_post( $post );

	if ( ! $post ) {
		return false;
	}

	$lock = get_post_meta( $post->ID, '_edit_lock', true );

	if ( ! $lock ) {
		return false;
	}

	$lock = explode( ':', $lock );
	$time = $lock[0];
	$user = isset( $lock[1] ) ? (int) $lock[1] : (int) get_post_meta( $post->ID, '_edit_last', true );

	if ( ! get_userdata( $user ) ) {
		return false;
	}

	/** This filter is documented in wp-admin/includes/ajax-actions.php */
	$time_window = apply_filters( 'wp_check_post_lock_window', 150 );

	if ( $time && $time > time() - $time_window && get_current_user_id() !== $user ) {
		return $user;
	}

	return false;
}