Not the first
Yes there is a key number on the ignition barrel. You need to open the control box in order to obtain that number.
Then contact your local Suzuki dealer (usually have to give serial number of motor too) and a replacement key will be supplied.
Don't forget your engine lock key if like many it's on the same ring. I always keep them separate (so if you leave the keys on the boat in error, nobody can remove the motor etc) but you'd be surprised how many dont!
Hope your back on the water soon, perhaps it's an idea to buy two keys whilst your at it....
Peter ~ firstname.lastname@example.org
~ 07930 421007