SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '15d10f6adfdb024a13417650509096f511bd56e3d0b42fdfec7c3fc51c32e2d6' 
  AND token = 'oqEbJFbUi5Mskz2WooekSYvoI2XwKrhXoUUhOOe8Jbk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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