If you're using a regular spare tire like your original tires then yes of course it would be okay to drive on the highway with that spare tire and at normal highway speeds.
If you mean is it okay to drive on the highway with a spare Donut tire then yes it's okay to drive on the highway with the Donut Tire but do not exceed 50 MPH with the donut tire and try to get your regular tire replaced within 70 miles of driving on the donut tire if possible.
Donut tires are only meant to be used temporarily so get your regular tire replaced as soon as possible.