(a) The date of maturity of an instrument creating a lien upon real property is considered to be 10 years from the date of the instrument, unless
(1) the period of the instrument is disclosed by the terms of the instrument; or
(2) another instrument extending the period of the first instrument or a memorandum of payment of the first instrument is recorded.
(b) When an existing recorded instrument is recorded before March 26, 1955, which creates a lien upon real property but which does not disclose the period of the instrument, another instrument extending the period of the first instrument, or a memorandum of payment of the first instrument may be recorded before January 1, 1956.