There's no need to worry. Getting pregnant isn't that easy.1
It's unlikely that sperm survive for 2 hours.
On a dry surface, such as clothing or bedding, sperm are dead by the time the semen has dried. In water, such as a warm bath or hot tub, they'll likely live longer because they thrive in warm, wet places. But the odds that sperm in a tub of water will find their way inside a woman's body and cause her to get pregnant are extremely low.
But let's assume the sperm has somehow managed to survive on the toilet seat or whatever you are proposing.
The sperm would then have to enter the female body via the vagina and travel through the uterus to the ampulla of the uterine tube for fertilisation.
Image Credit: pathologyoutlines.com
basically literally impossible.
But let's assume that, for the sake of the argument, the male sperm actually has travelled there. Even then, one can only get pregnant during ovulation, which is roughly 10-16 days before the female period in the menstrual cycle. Sperm only survives for several days (let's be generous and assume 4 days) in the female body, meaning that timing is pretty important. This means the chance to get pregnant at a random day is roughly 1/7.
1: This is one reason why IVF exists, and why quite a few couples have problems getting a child.