SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd91eb884060bc4a7f796142ab3e635681a84430c0100f92edf01a841dee23859' 
  AND token = 'v8Rc58fua+LwtbyQ3x1U0QhOxBrgFsiqkRL0QmH1JFs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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