In all cases of foreclosure of mortgages or deeds of trust heretofore executed (or that shall hereafter be executed) by any railway company organized under the laws of this state, or of the territory of Kansas, upon the property or franchises of such company, whether the same shall be now pending or shall be hereafter commenced, no sale shall take place at the instance of the trustee named in said mortgages or deeds of trust by virtue of any judgment, decree or interlocutory order entered therein, until after the expiration of three years from the entry or docketing thereof, except as hereinafter provided.