Looking at the election with our current knowledge, it's clear that Lincoln's election was the final spark that set off the civil war. Did Northern voters realize that a Lincon victory meant likely war?
While they might not have known for certain that it would have lead to war, around the time of the 1860 election there was already quite a divide in the nation between those who were for slavery, and those who were against.
Secession wasn't a new idea in the United States, as it had been mentioned more than once. South Carolina in particular threatened to leave the union over the issue of tariffs in the 1820's (https://www.apstudynotes.org/us-history/topics/nullification-crisis-/).
The election at the time was a big one, because of the growing issue of slavery between the North, South, and the emerging West. The Democrats in particular were having trouble picking a candidate over the issue of slavery, because they felt Stephen Douglas wasn't strong enough in his stance on slavery (http://www.ushistory.org/us/32d.asp).
Lincoln was a supporter of admitting western states as free states, and the southern states really didn't like that. He didn't win the votes of a single southern state, and only got 40% of the popular vote. Feeling like their votes don't matter and their interests aren't important to the nation, South Carolina seceded a few weeks later, with the others to follow.
The South was very openly against Lincoln's election, and they were very openly against the idea of the west being comprised of free states. As a Northern voter with the knowledge of the South's previous threats and how huge of an issue this was at the time, you would have known that the issue would have started the civil war. You probably wouldn't have thought that It would have led to the big, long war that it did, but you would believe it would lead to a rather short conflict.
Edit: /u/Master_Of_Knowledge has pointed out, I failed to mention the border states in this issue. Most of the slaveholding states were all for secession over the issue. Although the border states did not leave the union, they still did not want Lincoln as president. If you look at the picture at the top of (http://mrkash.com/activities/election1860.html), you see that no border states voted for Lincoln. None of the slave states wanted Lincoln to be president because they didn't want to lose power, and they didn't want their economy to suffer.
I wouldn't say that it's quite as simple as saying "a vote for Lincoln meant certain war." There was a range of political feelings at the time. It might be illustrative of that range if I dredge up an old answer from a similar thread, which talks about attitudes in a border state (Missouri) before the war. Missouri was unique in that it had a majority (around 17,000) of the total votes for Lincoln that he got in all the slave states (about 27,000).
If this is helpful, let me know; or if you have questions, let me know that too. The Civil War and the immediate aftermath is not my current primary research interest but it was the topic of my graduate school work.