Calculating the average key search time of DES
At $10^6$ keys per second, going through the full $2^{56}$ keys would take $2^{56}/10^{6}$ seconds, or about 2200 years; the average time would be half that (or a bit more than 1000 years).

Obviously, this is longer than anyone would be willing to wait.  So, why is DES considered brute-forcible?  Well, we can throw considerably more resources at the problem than a single laptop...