Merge pull request rails#42987 from entretechno/simplify-pluck-value-first-to-pick-value

`ActiveRecord::InternalMetadata.[]`: Simplify `pluck(:value).first` to `pick(:value)`

Author: kamipo

activerecord/lib/active_record/internal_metadata.rb

@@ -32,7 +32,7 @@ def []=(key, value)
       def [](key)
         return unless enabled?
 
-        where(key: key).pluck(:value).first
+        where(key: key).pick(:value)
       end
 
       # Creates an internal metadata table with columns +key+ and +value+