SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '909ce4e7e957828d4948758b8a1b55e027e53107b9a3fc4cfb224497e9f71732' 
  AND token = 'osO3lmkgYnIvDZJr/1nL7jjCvbYqXbzVrgNrvGaHSWc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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