Just state your destination and the fact that you are a pensioner.
e.g. "Pensionista Santa Pola"
or "Dos pensionistas Santa Pola por favor"
The person in a ticket office may ask for ID. I have only been asked
once when my wife was not present. When she appeared and produced her driving
licence, that was sufficient. I think anything with your photo and D.O.B will do.
Keith