SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd8648fd25ba0f0d6fa737077b629981afdbd06d7d5418ae6a79ebea251e30fa3' 
  AND token = '16E46zMnMT+fbrt3KC/YtzS1LEEPz9E0Bi5M9xb/IsY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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