OK. I believe this is simply how aliases work. Since your alias is actually a collection of indices, Elasticsearch has to look inside each one to determine if there are any documents that match the criteria of your search.
That is, you've asked it for data in the last 24 hours, but it doesn't know what data might be included as part of that collection of indices without looking in each one.
I believe the alias functionality in Elasticsearch is simply a way to control how data is read and indexed, as well as being a handy shortcut for querying multiple indices while specifying a single index. I don't personally have a lot of experience with them though, so there may be a way to give your alias some context about what data lives in which underlying indices, or otherwise restrict which indices it looks in, but I don't know of a way, and I don't see anything in the docs about that. You might try asking about it over in the Elasticsearch section, they'd certainly be more knowledgeable about aliases or other solutions to what you are trying to do than I am.
I hope that explanation about why it works that way at least makes sense though.