SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e51c3e299e2df69772c2c9755b0cb20ab79bd45d2c465c380247e0be51709de2' 
  AND token = 'lX+gH8TpeS27q0PtrGzfbX40V5Jvl7Zn6+hqRiT+S9s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00015

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