Another approach could be preallocating hashed of your timedate, then looping over your file, and write the data out. Maybe leave out the seconds, as that might sometimes not be :00 depending on the load of the system

This code might help to loop, and prepend 0 to numbers smaller than 2 digits:

# First, we read the file, put the data into a hash
# now, we loop on the day:
$day = '2016-02-06';
for $hour (00..23){
  for($min=00;$min<60; $min+=10){
    $key = sprintf("%s,%02d:%02d", $day,$hour,$min);
    print "Checking if $key:00 exists\n";
  }
}
[download]

ps: The real world solution is using a RRD (round robin database)