Read the manpages for shadow(5) to see the field layout. You should be able to determine days / dates for expiration from there. (I'm not sure about a command that does this for you.)
If there is an exclamation mark (!) in the hashed password field, the account was manually locked.
Note that there are lots of ways to prevent logins, so just because you don't see something obvious in /etc/shadow doesn't mean the account is necessarily usable.