SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '789b23a8fc06af8b90c45bee3ad2f33b62628570d320c0d2adab490759afec8d' 
  AND token = 'uS4uDQ1xPgVxSrRo8UhIFrlHeWzD8tQ8Z2hufCm6+J4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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