SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4cd9ad04a866950cee94856466e46260f4467bbdfa33c71a294e0b5807a83c90' 
  AND token = 'l/BXJ/vJaiCvjuA5kNrRVGyW3Qrwh3cOt68p9QfhzvM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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