Minecraft wiki entry for Lava, associated text: 2.5 seconds with no armor
3.5 seconds with full leather armor, no enchantments
4.5 seconds with full gold armor, no enchantments
5 seconds with full chain armor, no enchantments
6.5 seconds with full iron armor, no enchantments
12.5 seconds with full diamond armor, no enchantments
12.5 seconds with full netherite armor, no enchantments