Question

it shows 1 Key found does that mean that the key is still working?

No, that's not what it means. It just means that SG found one key you input for your giveaway.
SG has no way to check for working keys.

There is no way to know a key is still valid. May i ask what key?

There's no way to check if a key is duplicate or not, except if you try to activate it.

Key isnt anything nice, just a random key i got from a friend

Post the key here and I will tell you if it's still good.