SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '79b540aaaf76797001609fbf913235175daf74f7253cd52cd4c2237af7086f01' 
  AND token = 'OBt1mGxmC4yd9SngCNQQfCwJMQY8t0b4kONS+jvVyKU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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