PHP：读取超时错误

I am facing a read timeout problem from couple of days.

1. There is a facility to upload users in my application (Xls,xlsx are allowed extensions). This is completely admin panel.
2. I am using PHPExcel for reading the data from the sheet and inserting each row details into database on the fly.
3. Here, there is a possibility to upload large size files. Right now the file I am having is 16MB file which contains nearly 200k records.

4. I have increased below configurations through htaccess

   php_value memory_limit 1024M

   php_value max_execution_time 259200

   php_value max_input_time 3000

   php_value post_max_size 700M

   php_value upload_max_filesize 100M

I have placed set_time_limit(0) in the specific controller also.

My problem is read timeout in production environment. It is executing for around 15 mins and returning the below error

The requested URL could not be retrieved

While trying to retrieve the URL: http://example.com/upload/url

The following error was encountered:

    Read Timeout 

The system returned:

    [No Error]

A Timeout occurred while waiting to read data from the network. The network or server may be down or congested. Please retry your request.

Will Keep Alive do something here. It is set to 5 in production and Apache timeout is 300.

I have searched many of the similar errors post in this site but no luck

I am planing to set a cron job, uploading the files only from front end. Hope that will solve this but I also want to know what factor is causing this error.