SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6d8f99eb7d284627e730bc517cd33f2d19f517056f6d69361eb11021755aa411' 
  AND token = 'QRiBcTmY0OD5Vkzm8cGpIuSqWVq+jGx5C8pA7Ugdd+w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00049

JSON explain

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