Málaga airport to the centre at 11pm – train or just get a taxi?

The Cercanías C1 train does still run at that hour – the last one leaves the airport just before 01:00 – so with a 22:45 landing you should make it comfortably once you have bags. It is €1.80 a head and about twelve minutes to María Zambrano or Málaga Centro, then a short walk or one stop onward. That is what I would do for two people. A taxi from the airport rank has a fixed minimum for airport journeys, so expect somewhere around €20–25 at night for the two of you plus cases. Uber, Bolt and Cabify are usually a few euros cheaper if you would rather be dropped at the door with the luggage, and at that time of night the roads are clear. For Plaza de la Merced specifically, the train plus a five to ten minute walk is fine unless the cases are genuinely heavy. Full breakdown with current prices is in our airport to city centre guide. Do you know yet which terminal exit you will come out of?