SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '31dbc7a21ec672234d57bab47b2e51d680c4101c00427fd81582cf617d2c12f2' 
  AND token = '5b5TNX2DyqTPo8p3Z5HijTzBbO7XvP0KWZpy8DOs+ns=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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