SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '8f16ccc9fef372ebe1541465df0056567cef0972da89007afc014edb4633d570' 
  AND token = 'UxH0pr9hwzfZo1QfZURXn9z+hBNevK34OHyPsWeMogw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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