No order for a warrant, and no warrant drawn pursuant to Section 42647, shall be drawn in favor of any person employed in a position requiring certification qualifications, unless such person is at the time the holder of a proper certification document in full force for the full time for which the requisition or warrant, as the case may be, is drawn, and on file or registered as required by law at the time and unless he is employed by the governing board of the unified school district, or district with over 10,000 average daily attendance or by the county superintendent of schools as provided in this code.