That depends on the engine. Check the owners manual. Here it says it is done every 12.5K miles or one year but this is only for the diesel car:
https://www.mazda.co.uk/buying-owning/maintaining/service-schedules/So your 7 years bargain will need to have gone through everything up to 87.5K miles.
Mazda does not have big services. You always do the same things, change the oil and the filter, and every other service you add extra filters, brake fluid, etc.
If you want to buy the diesel one, have a gentle read about timing chains and oil pick up. If your bargain is on a genuine 48K miles without annual oil changes and without knowning whether it was driving only for the school run and the supermarket, it may cause you a lot of headache.
If you want to buy the petrol one, be aware that it runs around 20mpg.
As there are not a lot of them left for sale, most of them are auction cars that have been part exchanged and because they did not meet the franchise dealer criteria, they are sold through the auction. So be aware that things will not be perfect on them, on top of the typical faults.