SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9c50868d0b85fd27e16ac6c01ad01b68a1bcdeec2a321a27906cb8f1ac1b6479' 
  AND token = 'gWZh+shKKr8aVLkEf+OaaGYXCagRzKnSUStcxsTa4T8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

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