"Conveyance" defined

The term "conveyance", as used in this act, shall be construed to embrace every instrument in writing by which any estate or interest in real estate is created, alienated, mortgaged or assigned, or by which the title to any real estate may be affected in law or in equity, except wills, leases for a term not exceeding three (3) years, executory contracts for the sale or purchase of lands, and certificates which show that the purchaser has paid the consideration and is entitled to a deed for the lands, and contain a promise or agreement to furnish said deed at some future time.