SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '656540cc844bb4bf5df949985df6941fcb63bf468368eb2a83f93c9a0a4c39b5' 
  AND token = 'rVZiOLLzDZe0lMkWefst5yTqt3UY66Y7YbCCtpXPSL8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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