Preheat your oven to 250°F (120°C).
In a large mixing bowl, combine the Corn Chex cereal, Rice Chex cereal, pretzel sticks, and mixed nuts. Mix well.
In a separate small bowl, whisk together the melted butter, Worcestershire sauce, garlic powder, onion powder, and salt.
Pour the butter mixture over the cereal mixture and gently toss until everything is evenly coated.
Spread the mixture onto a large baking sheet in a single layer.
Bake in the preheated oven for 1 hour, stirring every 15 minutes to ensure even baking.
Remove from the oven and let it cool completely before serving.
Store in an airtight container to maintain freshness.