Extra in EXPLAIN printing - 'Impossible WHERE noticed after reading const tables'

I have a simple table called 'million_words'. It has one row with two columns -> id INT UNSIGNED NOT NULL AUTO_INCREMENT PRIMARY KEY & word VARCHAR(50 NOT NULL.

I run this query -: EXPLAIN SELECT * FROM million_words WHERE word = '-anon'

The Extra column then prints : 'Impossible WHERE noticed after reading const tables, even though the row is clearly present in the table.

Whats wronf