SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '38c3fe9a8d96d061971ec04e6aefad3a7451c3ca16663814c65bcd6efb788b53' 
  AND token = 'Kxz6gvrcBz5KkWd2MxLFehrf7jgVij2/HRE+V6wVctk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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