SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2c61e91446b9016862025d71ad3d69160d5ba640ff3fb65c3eaacf4aa75a5196' 
  AND token = 'JNs5Oq6dD7jKls7+y8HUR2vyq6pi52bajUsdr5An740=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}