Mo. Rev. Stat. § 516.150
No suit, action or proceeding under power of sale to foreclose any mortgage or deed of trust, to secure any obligation to pay money or property, shall be had or maintained after such obligation has been barred by the statutes of limitation of this state; nor in any event after the lapse of twenty years from the date at which the last maturing obligation secured by the instrument sought to be foreclosed is due on the face of such instrument, unless such termination of said period falls within two years after the passage of this section, or has heretofore happened, in which event such suit, action or proceeding may be begun within two years after the passage of this section without regard to the date of the instrument or the maturity of the obligation, unless otherwise barred under the provisions of the general statutes of limitation, unless before the lapse of said twenty years the owner of the debt thereby secured or some person for him shall file an affidavit duly verified, or file an instrument in writing acknowledged as deeds are required to be acknowledged in order to entitle them to record in this state, showing the amount due and owing thereon.
§ 516.150, RSMo
RSMo 1939 § 1017