SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'be868e21048993fd6597b3c9bd46d88372a72e79198a573a17402ca0d24f692c' 
  AND token = 'W5W9nF9UFswuMM+JmOiXGpqFpK6/6ztFYcJxEQbHofg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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