Integral lockable hasp by Seachoice
Seachoice makes an excellent alternative in a "Lockable Hasp with 2 Keys", p/n 50-37031 or BMD50-37031. Similar to the swivel hasp mentioned in other responses you've received, but it comes with its own lock. On my previous H22 I opted for the swivel hasp and then added combination locks when needed. However this alternative I find quite convenient, and they are keyed alike. This eliminates storing the combo locks (and remembering where you last put them), and when in the unlocked position the hasp simply opens freely for quick safety access. As you can see from the link they aren't the cheapest option, but compared to buying hardware and locks for each lazerette, I find the marginal premium for the added convenience worth it.