I know that a lot of dramas especially jdramas and cdramas have most of the time 45 min per episode,but this doesn't happen with korean dramas , so I'm looking for dramas like that. This way I can marathoon the drama more easily haha

Thank you in advance :)

Korean dramas have their assigned time slots and thus usually run for an hour. Daily dramas can have shorter episodes but the run is more like 100+ episodes overall. Sitcoms, likewise, are also short in airtime (usually 30 min) but long in episode count.

I don't know much about web dramas but as I understand it, they tend to be really short - both in airtime (15 min?) and episode count.

That said, there might be outliers. The only one I can think of: The Lover had 50 min episodes (it was broadcasted by Mnet).
She is wow has 12 episodes with 50mins each.
Maybe you would also like dramas that have only a few episodes, but still are a hour long. KBS has those drama specials. These are mostly only one movie, but there are some that have a few episodes. My favorite would be White Christmas (8ep), Sirius (4ep) and Adolescence Medley (4ep).
I've just seen that Reply 1997 also has 50min episodes. Some of the high school dramas tend to have a shorter amount of episodes (Cheer Up) and also the music dramas from mnet (Monstar, Presevere Goo Hae Ra).
47 Min: I Need Romance 3, Dating Agency: Cyrano

45 Min: I Love Lee Tae Ri, The 3rd Ward, I Need Romance, Who Are You (2013), Surplus Princess

40 Min: One Well-Raised Daughter (122 eps), Smile, Dong Hae (159 eps)

30 Min: Full House Take 2 (32 eps, so it's like 16 eps of 1 Hour), Vampire Idol (79 eps)
Thank you guys so much <3
I had no ideia that some of the dramas you said were in the 40 mins :D
Gonna do my search haha 
Because It's First Time mostly 45mins.
@Tarida I'm actually watching Because It's the First Time ,but thanks for the help .I really aprreciated it :)
The Lover has 40+ minutes run time, except for the last episode