For the service of subpoenas ad testificandum issued out of any of the courts of this State, there shall be allowed and paid as follows:
Serving each subpoena, thirty-five cents ($0.35).
Mileage, computed from the place where the subpoena is made returnable, for each mile actually traveled, four cents ($0.04).
The provisions of this section shall not apply to cases in behalf of the State where the officer serving such process is paid a salary or per diem.