Fastest way to find files modified in last 'x' minutes

I have a requirement to find files modified in last 10 minutes in a directory. The directory keeps getting updated and it will have around 50k-60k files every time. I'm using the below code to get the files:

import java.io.File
import java.time.Instant

val dir = new File("/path/to/dir") 
val files = dir.listFiles.toList.filter(f => f.getName.matches("some filter"))
files.filter(f => f.isFile && f.exists &&
    Instant.ofEpochMilli(f.lastModified).plus(10, MINUTES).isAfter(Instant.now))
    .toList.sortBy(_.lastModified)

This takes around 20-30 minutes to run. But I want to get the results in less than 10 minutes.
I even tried running this in our hadoop cluster using spark. This is the spark code:

val sparkConfig = new SparkConf()
    .setAppName("findRecentFiles")
    .set("spark.serializer", "org.apache.spark.serializer.KryoSerializer")
    .set("spark.shuffle.compress", "true")
    .set("spark.rdd.compress", "true")
val sc = new SparkContext(sparkConfig)
val rdd = sc.parallelize(files)
rdd.filter(f => f.isFile && f.exists &&
    Instant.ofEpochMilli(f.lastModified).plus(10, MINUTES).isAfter(Instant.now))
    .collect.toList.sortBy(_.lastModified)

Still it takes the same time. And one thing I noticed is that filtering based on the file name is fast. But adding the lastModified filter makes it slow. Is there any better way so that I can get the results faster?

UPDATE
I updated the spark configs and now I'm able to get the results in less than 10 minutes. Earlier, I was running the jar like this:

spark-submit myJar.jar

I changed it to this:

spark-submit --deploy-mode client --queue SomeNonDefaultQueue --executor-memory 16g --num-executors 10 --executor-cores 1 --master yarn myJar.jar

Also removed set("spark.rdd.compress", "true") from code as it increases the CPU time, as explained here - https://spark.apache.org/docs/2.3.0/configuration.html#compression-and-serialization

The problem is the stat() check to get last modified comes after a linear search through the directory to look-up the name. If you can change the directory format, add subdirectories (calculated by file name) and try to group the number of entries in each subdirectory to ~1000.

Otherwise, create a map of name:lastModified and use the WatchService to update the map whenever an event is fired.