SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd9d5b84ee9c4c61f8db4d76678676304cf42aafdc74a2574cc0208aeb0e6da78' 
  AND token = 'yi5YPCWx4OIdjIwXkGiakwXFgTcF+DoisTbmUJ6qDxs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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