Available since: 7.0.0
Time complexity: O(1)
PEXPIRETIME has the same semantic as
EXPIRETIME, but returns the absolute Unix expiration timestamp in milliseconds instead of seconds.
Integer reply: Expiration Unix timestamp in milliseconds, or a negative value in order to signal an error (see the description below).
-1if the key exists but has no associated expiration time.
-2if the key does not exist.