Locking and unlocking card?

Hello, new to WS. Until I figure out what my options are, I have everything in my cash account. With the card being debit, I’m slightly worried about a (far fetched, I know!) scenario where everything could be emptied. Delighted to see the “lock card” option, but wondering if locking and unlocking is instant? Can I unlock in a store, make a purchase and then lock it again, is it that easy and fast?