Mix cereals, cheese crackers and corn chips in large microwavable bowl. Set aside. Microwave butter in small microwavable bowl on HIGH 40 seconds or until melted. Stir in Seasoning Mix. Pour over cereal mixture; toss to coat evenly.
Microwave, uncovered, on HIGH 5 to 6 minutes or until cereal is crisp, stirring every 2 minutes. Spread snack mix on foil-lined baking sheet. Let stand until cooled to room temperature. Store in airtight container.