SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '535f6f018d93f3d58825b093adee8b1ae504143c5df959bdf8de7af46093171d' 
  AND token = 'ZsFFjNz0MXrXgo6f/nrWIw/tfnI5HySgjgVPqwDLxHY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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