SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2452fbb58870f0fce03382491426b9d320082deceaca20de9c54f17f533c4344' 
  AND token = 'BOz/qRwrA2SbhSlUUsAHfiDiSeDJq6tXdlypSKDPUrI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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