Making DropCreateDatabaseAlways work with custom DbMigrationsConfiguration - entity-framework-6

Question

Using ef6 code first and mysql I got the following exception:
Specified key was too long; max key length is 767 bytes.
To fix it I created custom HistoryContext and shortened ContextKey length.
And to use MyHistoryContext I created Configuration class inherited from DbMigrationsConfiguration<MyContext>.
After creation of Configuration class DropCreateDatabaseAlways db initializer stopped to work throwing:
The DropCreateDatabaseAlways initializer did not drop or create the database backing context 'MyContext' because Migrations are enabled for the context.
A̶n̶d̶ ̶s̶e̶t̶t̶i̶n̶g̶ ̶A̶u̶t̶o̶m̶a̶t̶i̶c̶M̶i̶g̶r̶a̶t̶i̶o̶n̶s̶E̶n̶a̶b̶l̶e̶d̶ ̶t̶o̶ ̶f̶a̶l̶s̶e̶ ̶d̶i̶d̶n̶t̶ ̶h̶e̶l̶p̶. (I've understood that its unrelated.)
Edit.
I want to reformulate the problem: creating Configuration class inherited from DbMigrationsConfiguration<MyDbContext> (to use custom HistoryContext wich solves Specified key was too long problem in mysql) made ef think that I've enabled migrations via Enable-Migrations command and DropCreateDatabaseAlways stopped to work (but this is intended behaviour as far as I understand). But afterall this is not a big problem because I can create custom initializer with
context.Database.Create();
context.Database.Drop();
So, did I understand it correct?
Custom HistoryContext:
public class MyDbHistoryContext : HistoryContext
{
public MyDbHistoryContext(DbConnection existingConnection, string defaultSchema)
: base(existingConnection, defaultSchema)
{
}
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
base.OnModelCreating(modelBuilder);
modelBuilder.Entity<HistoryRow>()
.Property(x => x.ContextKey)
.HasMaxLength(255);
}
}