The commissioner of public lands hereinafter referred to as the “commissioner” is hereby authorized to execute and issue in the name of the state of New Mexico, as lessor, leases for the exploration, development and production of oil and natural gas, from any lands belonging to the state of New Mexico, or held in trust by the state under grants from the United States of America, and including lands which have been or may hereafter be sold by the state with reservations of minerals in the land, such leases to be issued upon such terms and conditions as the commissioner may deem to be for the best interests of the state, and not inconsistent with the provisions of Chapter 125, of the Session Laws of 1929 [19-10-1, 19-10-12 to 19-10-25 N.M. Stat. Ann.], and amendments thereto, provided that this act [19-10-1, 19-10-2 N.M. Stat. Ann.] shall be effective only as to such leases issued subsequent to the effective date of this act; and, provided further, that nothing in this act shall affect or disturb valid existing rights as to any carbon dioxide lease heretofore issued under the provisions of Chapter 177, of the New Mexico Session Laws of 1937.