Yes there is... 

Step 1 : Open your device’s dialer (App where you enter telephone numbers to call someone).

Step 2 : Dial the below code, it will automatically open a new windows. (if it doesn’t open a service information window on your device, you can often only access the status via fastboot) 

*#*#7378423#*#*

Step 3 : Now in that window go to Service Info >> Configuration, and see if there is :

Bootloader unlock allowed - Yes  
Bootloader Unlocked - Yes 

Summarized from https://thebroodle.com/android/how-to-check-your-bootloader-is-locked-or-unlocked/