Child Safety Cabinet Lock

My son always had a playpen but only use it when we travel in place of a crib.
Lately, I feel like I am going crazy. He is very stubborn, and makes trouble. He is a good boy but I feel like that he suddenly can do everything, like open the cabinets that have child safety locks!!!
So, I put him for a minute or two in his crib as time out, and then he relaxes and start playing with his books and toys. So basically I was thinking why don't I bring his playpen to the living room and letting him play in it for a 15 min or 30 while I eat or something. If it's bad for him I won't do it. So please give me advice without shallow judgments.

Thanks
You know the child safety locks for the cabinets and drawers, you have to push down on the little thing to be able to open the cabinet. Well, he knows how, he saw me and his dad doing it and he learnt how!!!