SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '92538b2da60aecf747fe3bd26146ceb35d4097c18e16cd97e2265a6b58daff75' 
  AND token = 'KsCLmDY1Jpjo466jYOdab5EbV4KVed3qfjZBYJNY9WM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}