SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0626434ef3e6f167d83a8905c2045afd0269e0809cdecf03da1be2ce8510d834' 
  AND token = 'H5iNhcE36upl1GvmDBpNcOgITaONUvMwaZVWh1b076Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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