Generally speaking, facts are not protected by copyright. Based on that, looking at the website of a single shop to find out the opening hours would not be problematic.
However, databases of facts can enjoy legal protection in some jurisdictions, especially in the EU. And info for the hundreds of supermarkets of a chain is probably substantial enough to count as a database as well. So in my (non-expert) opinion, it’s not an unambiguously legal source, and it’s better not to copy from it without explicit permission.