Think of it like this:
- you unlock your account, that's been in some state, say for a few days/weeks/whatever
- the server that controls the accounts sets a flag, saying it's a good now, for the other servers that have the account data
- the change "propagates", which can take a little while, depending on network topology, system design, data-flow, and other issues, sometimes a few seconds, but often more on the order of minutes or hours, occaionally a day or two, but that's unusual