Any county road, or part thereof, which remains unopen for public use for a period of five years after the order is made or authority granted for opening it, shall be thereby vacated, and the authority for building it barred by lapse of time: PROVIDED, That this section shall not apply to any highway, road, street, alley, or other public place dedicated as such in any plat, whether the land included in such plat is within or without the limits of an incorporated city or town, or to any land conveyed by deed to the state or to any county, city or town for highways, roads, streets, alleys, or other public places.