function update_expiration( $key, $expiration = WP_FS__TIME_24_HOURS_IN_SEC ) {
            $this->_logger->entrance( 'key = ' . $key );

            $cache_entry = $this->_options->get_option( $key, false );

            if ( ! is_object( $cache_entry ) ||
                 ! isset( $cache_entry->timestamp ) ||
                 ! is_numeric( $cache_entry->timestamp )
            ) {
                return false;
            }

            $this->set( $key, $cache_entry->result, $expiration, $cache_entry->created );

            return true;
        }