Yes, use your ignition key to unlock the rear seats. Not sure if you have an Accord EX, or LX, but find the locks directly behind each rear seat's headrests- one lock behind each headrest. You will then pull the rear seats forward- exposing the opening to the trunk (or boot). From there, you will see a small rope- pull it. That rope is the emergency trunk release designed to help kids should they find themselves locked in the trunk.
There is no trunk release button on your key? There should be a keyhole in the rear taillights for the trunk release. If those two methods fail or are unavailable, then try Rick's method of going through the rear seats. BTW, which country are you in?