SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0c8593e844483b9580e6a102efa1b438d982bb4296a42c414a9182e9568db539' 
  AND token = 'TJGUIHswsp+xzS/z+ob+tVgU5fzoTWwEdofM4/vJqZU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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