Which laptop to buy under 45000 rs?

It would be good to look around further. You are looking for gaming and the graphics cards in these are very low performance.
https://www.notebookcheck.net/...849.0.html
Lenovo has GT 920MX, rank 228. HP shows R5 M430. That is lower rank 357 as lower performance.
Intel Integrated HD Graphics 520 is when on battery rank 363
228 NVIDIA GeForce 920MX
357 AMD Radeon R5 M430
363Intel HD Graphics 520

You need Windows Operating system for gaming.
I'm looking for a GT 940M as a minimum in graphics processing.
https://www.flipkart.com/...NQ8TJEYPMQ
shows an error in gpu
https://www.vijaysales.com/Acer-E5-575G-NXGDWSI006-Laptop-Core-i3-6100U-4GB-RAM-1TB-HDD-2GB-Graphic-15-6-39-6-cm-Win-10/4994

It has a low quality screen, keyboard, touchpad, and in sluggish in i3-6100U, but GTX 940M or mx runs games much better than Lenovo with i5-6200U and 920MX

https://www.flipkart.com/...G6CTQN9HKQ
Asus R558UQ i5-7200U GT 940MX 1920x1080 display. The higher resolution display brings fps down in modern gaming, but has the newer i5 and best graphics card for the price
Last one in red at 42089. Available under 45k at other stores in other colors.
http://www.amazon.in/...B01MRN89V8

You can search each store, and you should find 6th or 7th generation core i5 with a GT 940MX, best in GDDR5 and really can use 8GB ram and will need Windows, but is available at 40,000 to 45000
http://www.amazon.in/...06VVKJHG8/

Says GT 940MX GDDR5, i5-7200U, 1920x1080 and not doing better than that:
https://www.snapdeal.com/...8941405200