SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '353a548ca06b23c0deed70684371620a81f4f88ac5469771f04f6f05bef67dd9' 
  AND token = 'YBU5t0K+YDJDHcz7pW0kz0mgnJquJjKEYSWB4+T+HH0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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