I am not a server administrator, all the information about servers is to my best knowledge.
Servers don't have an explicit setting to keep them at daytime, but it seems like you can define the time a server starts at after a restart.
Server operators MAY frequently restart their rented instances in order to keep the time at a certain point..
This explains why you currently can't search for these servers using a specific filter.
You can however filter for some strings in the host filter. (ommit quotes)
This isn't a guarantee for daylight servers. Servers currently on nighttime are usually low populated, so this is another thing to look out for.