Before any benefit provided for herein can be paid, all conditions applicable to the payment of the benefit must be met, application for the benefit must be presented to the retirement board in such form and manner as the board shall determine, and the payment of benefit must be approved by the board. If any retirement benefit provided for herein is less than twenty dollars ($20.00) per month, the board in its discretion may pay the actuarially equivalent value of such benefit in one lump sum, or in such other manner as the board may determine. Notwithstanding any provision of this chapter to the contrary, no benefit shall be due or payable before July 1, 1964, and no benefit shall be payable to a retired judge during any time he is employed by any city, county or the state of Tennessee or any political subdivision or instrumentality thereof.