SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '303a9160dfd6a1744bbe5ac81766826b977d6abb75d2435920142bed5c58c649' 
  AND token = 'm+umjuSm6DzXGSnmMmSCYyzNtr0017JDFs33qByf5kA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

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