How to check the occurrence of a string in a large csv file?

Question

Parsing

There is a csv file with a total weight of 50mb+ and there is a list of keys (list of strings). It is necessary to determine the occurrence of each key in csv at the lowest cost. At the same time, csv is located on a remote server (github) and is regularly updated.
Example:
There is a key "O. Henry". You need to determine if there is at least one occurrence of this key in the csv file.

Answer 1

Well, there is only one adequate solution: stop using csv for other purposes, study any SQL database and use it.

Answer 2

Perhaps it will help someone:
So far I have found one option - parsing in a stream using scramjet . It does not work at lightning speed, but with the current file size it is quite tolerable, with about a hundred keys and ~ 50MB of csv databases, processing took less than a minute.