There is a bit of a flurry of faulty/jammed ignition locks at the moment. Here are 2 examples. Top is a Honda, bottom is a Citroen. Vehicles were 10-15 years old and had quite a lot of use.
Sometimes ignition locks jam because the key is worn. In that case it’s simple enough to cut a new key to original dimensions. In the 2 cases shown above the lock barrels had failed. The lock/housings needed to be removed and replaced. Occasionally the lock isn’t at fault, it’s the ignition switch but it can be difficult for the layman to identify.
If your key is starting to become difficult to turn in both the ignition and the doors, the key is likely worn. If it is difficult to turn just in the ignition then you might want to think about getting the lock replaced before you find yourself marooned in a car park.
On some vehicles (e.g. a lot of VWs such as Polos, Golfs etc) just the lock barrel can be changed. In the case of Land Rovers, Volvos and the examples above it’s easier to just change the entire lock housing.