SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5ff6aec163428a4b27474b25aa5d605fd98bc015d14e963e1a708b7049fb7d73' 
  AND token = 'D07ws7QtGbrTB6aju1H+ahZBzjqdsJu+ZomeML91Koo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00014

JSON explain

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