Lightly toast the bread and brush both sides with melted butter; divide each slice in half diagonally and set on a dinner plate. Heat the butter in a skillet. When the foaming subsides, add the carrots and saute for a couple of minutes or until the carrots just begin to soften. Add the crabmeat and stir for a minute just to heat up. Add the lemon zest and juice and herbs; saute for 30 seconds and remove from heat. Season to taste with salt and pepper.