A. As used in this section, “real estate” includes a leasehold estate of not less than 25 years.
B. Notwithstanding the provisions of any law relating to interest or usury, contracts made for the loan of money, secured or to be secured by a first deed of trust or first mortgage on real estate, or by a first priority security interest in the stock of a residential cooperative housing corporation, may be enforced as agreed in the contract of indebtedness or other agreement signed by the borrower.
C. For the purpose of this section, an interest rate which varies in accordance with any exterior standard, or which cannot be ascertained from the contract without reference to any exterior circumstances or documents, shall be enforceable as agreed in the contract of indebtedness or other signed agreement.
D. Disclosure of charges in a disclosure given to the borrower pursuant to federal disclosure laws or regulations and acceptance of the loan proceeds by the borrower shall be deemed an agreement signed by the borrower within the meaning of this section.