Query to retrieve index details for a particular column in all tables
To check the column properties you can run the query

SELECT * FROM information_schema.columns WHERE table_schema = 'your_schema_name' 
AND COLUMN_NAME = 'created_at';


This will list all the tables in your schema with the columns created_at. Here you can check some of the column properties including the COLUMN_KEY with values PRI, UNI, MUL.

For a detailed view of the table index run the below query against the tables returned by the first query.
SHOW CREATE TABLE table_name;