SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f83a44985ac14b840edd4931660d783259a77da0856826a40f639171d4c54f72' 
  AND token = 'myLvWOvL6cRPykMTHhAVgWl88cwN5KjOukQELgMw/GA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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