SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '2b9518d7298eb75e7f0c930d1ee7968f5713a6939e38e486da5c4570a57d56e6' 
  AND token = '3VAI+ClDtTXQMQNsd5GJ34EqxQs1imXUb0PcTyI15KY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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