I haven't started this yet so all suggestions are welcome.

col_1 = integer between -180 and +180
col_2 = integer between 3000 and 12750
col_3 = integer between 1000 and 45000
col_4 = integer between 0 and 3
col_5 = timestamp(now)

I'm receiving data from a central server that I don't control and it must put it into a local MySQL database, but without any duplicates. A duplicate is when columns 1, 2, 3, and 4, are all identical to the incoming data. In that case I just want to update the timestamp, not insert a new line. If only 3 or less of the first 4 columns are matches I want to insert a line. What is the best way to go about this?