SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8aefb401b99a1cfb59adbca1b7d2f59e422632243910e56c66cbc3fb43afc139' 
  AND token = 'xNfR5AuAB6/BKlNEFnAaNOJRkstDS5jYHsc9sUyRl4A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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