With PHP 5.4.41 and memcached 1.4.24 it works in ASCII mode as well.
(PECL memcached >= 2.0.0)
Memcached::touch — Set a new expiration on an item
Memcached::touch() sets a new expiration value on the given key.
key
The key under which to store the value.
expiration
The expiration time, defaults to 0. See Expiration Times for more info.
Returns true
on success or false
on failure.
Use Memcached::getResultCode() if necessary.
This is only supported when binary protocol is enabled.
$obj = new Memcached();
$obj->setOption(\Memcached::OPT_BINARY_PROTOCOL, true);