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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e50c1945e8eea0d6832d12fa861452d43e7103d275a4fbf45bad37b21eb42422' 
  AND token = 'q/kXcQP6t6rZM/CiIUwKW5rafs7NUEQMqqpM5aVQ16w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00014

Explain
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE								Impossible WHERE noticed after reading const tables