SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2355a978d0e738ba6d448f13cc4a55dd68794101a066835b2f962c2812cde5eb' 
  AND token = 'GhcI0kQd12QRqL8hLCNr9h053JUZ/2r9usRejoLjEjw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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