The photon from its own frame of refference exists for exactly zero time, existing at all points uppon its tragectory. As Mangetout says they don’t experience time at all. So even if a photon has been according to us travelling continuously from soon after the Big Bang, without ever being absorbed. This 14 Billion (if I remeember correctly) Year old photon, from its own frame of refference has existed for 0 time.