In a mortgage of real estate, or any interest therein, the words "mortgage covenants" have the full force, meaning, and effect of the following words, and shall be applied and construed accordingly: "The mortgagor covenants with the mortgagee and his heirs, assigns, and successors, that he is lawfully seized in fee simple of the granted premises; that they are free from all encumbrances; that the mortgagor has good right to sell and convey the same; and that he does warrant and will defend the same to the mortgagee and his heirs, assigns, and successors, forever, against the lawful claims and demands of all persons."