SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c81b2f179a49cbfb386582eeae00b08f9b2d4348abb0a66e87e5ec327d59aea9' 
  AND token = 'YC5/ybPaphGDKH92h6Qt3/t+SGbNgXmY+/jlcB5wgwQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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