You did not list your state, but there is no state where the law entitles you to a paid lunch break. It is 100% legal for your employer to require that you take a lunch break, and some states where it is mandatory that he must. While no state that I am aware of requires an hour lunch, your employer may always, legally, require more than the law says, just not less.

The bottom line is that your employer is entirely within the law and you have no legal grounds on which to fight it.