Cook the chopped bacon in a medium saucepan over medium until crispy, about 6 minutes. Remove bacon, and drain on paper towels, reserving drippings in skillet. Cook the onion, celery, garlic, and thyme in the reserved drippings in saucepan until beginning to soften, about 3 minutes. Stir in the chicken broth, cannellini beans, chopped plum tomato, bay leaf, and kosher salt and black pepper. Bring to a boil over medium-high; reduce heat medium-low, and simmer, stirring occasionally, 8 minutes. Serve hot.