When a future entrant withdraws before age 50 after 10 or more years' service and attains age 50 while out of service, his age and service annuity shall be fixed as of age 50. He is entitled to an annuity, after he attains age 50, provided from the following sums:
The annuity shall be computed as though the employee were exactly age 50 when the annuity is granted regardless of his age at the time of application. No such employee has any right to annuity for any time between the date he attains age 50 and the date he makes application, nor shall any annuity be payable if he has received a refund of contributions.
40 ILCS 5/6-126