SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5801cf11729d4209971ccc36057453af6b7be31609cee673ecd6c740428b2cfc' 
  AND token = '9MHSDObjfb5LWtDUTxdob1rht2/HOpCI1nPacdEFCpU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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