“You have reached (name of the business). All our customer support executives are busy serving other customers. We will return your call within 1 business hour. Please leave your name, contact number and your message and we will call you back as soon our customer support executive is free. Thanks for calling and hope you have a great day.”
Caller ID and missed call alerts now serve as their own form of call messaging. People can see who called. They assume they need to contact you. It’s much faster to scroll through a list of incoming callers than to listen to recorded messages. Some people even use audio-to-text transcription options in their cars or from their mobile phones that turn voice messages into notes.

Feel free to add a personal touch to make your voicemail message fun and interesting. Clients will feel reassured when they know their messages have been received and you will get back to them.
You could add the words "After-Hours Service" or "After-Hours Line" after the company's name. That way there's no concern over whether it is indeed a number that reaches a real person who will return their call during non-business hours. It's a way to let them know they're on the right track. If that makes sense. :)