Boil 1 pound each halved wax beans and green beans in salted water until crisp-tender, 8 minutes; drain. Cook 1/4 cup sliced almonds in 3 tablespoons melted butter until golden, 4 minutes. Remove from the heat; stir in 1 tablespoon lemon juice. Toss with the beans and 2 tablespoons chopped chives. Season with salt and pepper.