Minecraft wiki entry for Lava, associated text: 2.5 seconds with no armor
3.5 seconds with full leather armor, no enchantments
4 seconds with full gold armor, no enchantments
4.5 seconds with full chain armor, no enchantments
5.5 seconds with full iron armor, no enchantments
10.5 seconds with full diamond armor, no enchantments
11 seconds with full netherite armor, no enchantments