SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '836311f23dd0aa5974ece1ffea8e717f3b4de347c30e94a90d9d25b04024b93d' 
  AND token = 'b/M1jjtenE4jpAoDunIblnspvgPwvS0W1EK0BirslKE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

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