SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ff3b4624c75482e54a6347d00a2d40ff5f731d1de0d175dea2a1fd19e71680e5' 
  AND token = 'LjIEkBaRh+mXu4W/mrOmhemC8W356u99TJcxc4omuSQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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