Essentially, there are two types of Intel processors – non overclocked versions, and the K or X variant, which is overclockable. For example, I have the Intel I7-7700K, which is overclockable. The I7-7700, on the other hand, isn't overclockable
all old processors are generally unlocked and can be overclocked. but if you are still confused, google it . if you also don't find anything on google. 
just follow the process, if you are unable to change  cpu multiplier in your system bios then, understand that your cpu is locked and not overclockable. if you are able to do it, and change it 
congrats your cpu is unlocked and can be overlocked. all the best?