Even as a writer of optimistic sci-fi myself, it's very difficult for me to come up with more than a handful of examples that are less than ten years old.
Becky Chambers is probably the single best young author working in this genre today. She's got two great series, one that begins with "A Psalm for the Wild-Built", and one which begins with "The Long Way to a Small Angry Planet".
I'd argue Andy Weir's "Project Hail Mary" is hopeful sci-fi, and the movie adaptation was great. You could perhaps put Adrian Tchaikovsky's "Elder Race" and "Service Model" in there too, since both are pretty hopeful in overall outlook. And if you broaden to include fantasy, Travis Baldree's "Legend and Lattes" series is very much in the same vein as Becky Chambers.
It seems like hopeful sci-fi movies and TV are more common, like the recent "Star Trek: Strange New Worlds".
Perhaps the recent troubles the world is undergoing will lead to more light-hearted fare to distract us? One can only hope.
Stargate SG-1 was maybe optimistic sci-fi.
Actually it was settled in the present but it was full of good human vibes and human values.
It had an incredible vibe of “humanity is good and humanity will stand against anything bad”. It was really naive in how it described the human nature but I’m sure it was deliberate.
And also it was fun.
Came to the comments to see if anyone was talking about Becky Chambers - thank you for not disappointing me! I picked up Monk and Robot with an intention to save it for an upcoming vacation, but started reading the first few pages early and couldn't put it down. I'm really looking forward to her next book in October.