SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '98e6c374f3c05a161b35acfb9c96428f2489bcf51c42468b6ea05ecccc8f1752' 
  AND token = 'SNRUImEJhYDnKnqBArlOOO8IRrNJMQhWARl49r9raqg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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