SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '99ea6734359cb6dbf1b91fe1ce9183394ed5cff284f2208993775a3785228f29' 
  AND token = 'UYBwuOuGoV4V6x5CG6zCGwKxky+93rt2VXVLz5D3mHU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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