SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '50513a68360eee9f6db6a3bed45e2309ec95641864431a4c6df9d5a80acd7a18' 
  AND token = 'eTa47f5X6nD2hqFS3uZVUD7UVxJ6DaO+baXB999SlBE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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