I've seen this topic a few times - and asked the question myself - about booking a room at one of the onsite Universal Studios hotels specifically to get hold of the room key which acts as the park Express Pass ticket. And about what time you can check-in to get the key etc.
I emailed the hotels and here's the reply I received. Hope it helps anyone thinking of doing the same.
"Thank you for contacting our Guest Services Department. We are committed to providing the most awe-inspiring entertainment experience possible to each of our guests.
All of Universal Orlando® On-Site hotels offer early "soft" check-ins, where you are able to settle payment and receive your hotel room keys as early as 7:00 AM. The Universal Express PlusSM that is offered with your room keys is valid through the end of the day of your check-out as well.
If you have any other questions or concerns, please call me at (407) 224-4233, option nine (9)."