SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '494335c87f340bd82743b5b153fd4470cfb60fa38b253f2c93f90fb5c0d8603f' 
  AND token = '+xpCy0gwurZbHdMMs8XgFZVROa1MCRGxaxvm7GD/zRQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}