SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '541c66880ca9dbb7cfb4f39bd562cf7ea31ba78335744e55c01639a2c937e71b' 
  AND token = 'DEWWUDfi/ImC6Z0ifINOkzodRB3lGfak5nx7E1WN5pY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

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