SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '426221839c38e17e0a44bb4847dbe6759c3afcf1364c709e3a026468f7da138e' 
  AND token = 'cGHbN9pYsqbUdH9bLQctteBXql6+FEuakfm512+oHOw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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