SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '256cdc5608d79d392faad6850b64814c79b3fe38cc68825d0e481a373123080f' 
  AND token = 'Re92iwQTevi+A4Va5IGnGHhc6RhNKo+PxeeQTkOGIVY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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