I can read your question in two different ways, so I will try to address both for you.
First, presuming you are an hourly employee, you are entitled to payment for the time that you work. If you are a salaried employee, or another exception exists, then your employer can expect work from you outside of specific "work hours". It is unclear from your question which category you would fall in, though I suspect it is the first category. If an employer does not pay full compensation to its hourly employees, there are statutes the provide relief. So, if you are concerned about being paid, then generally speaking, I would expect that you would have rights that you can enforce.
Now, it is also possible that your question is not payment related. What you might be asking is, "Can an employer order you to work outside of normal business hours, but with compensation?" This is a little bit different.
Arizona is an at-will employment state. This means that you, or your employer, can generally terminate employment at any time, and without any reason given. So, if an employer asks you to work, offers to pay for the work, and there is no improper motivation behind the request, if you say no, there is the possibility that an employer could terminate your services.
If this second scenario is what you are facing, I suggest you try to explain your particular situation to your employer - that you have responsibilities that preclude your ability to work outside of normal business hours. Good communication may prevent the loss of your job. Bad communication good lead to a termination.
I hope this answers your particular issue. If you are still unsure, you may wish to hire an attorney to find out more.