SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f27fed257671e1bd750d75d99e6b59b2ef62b77a6b3dcb8346c3e4b302483c8c' 
  AND token = 'irtWYIwpb0yPRzEv5NGFiYjMmM3t/nFJY0ZaX+q5EMU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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