SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3f23c0110cd0f83133208e91e12a18589737f6403c8e6514b85650e12f54db68' 
  AND token = 'QJ4El0rVibuzZV+ICBzijB2MoCrzO55RIy5cbu0Qf2M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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