SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b4b669c5579a725633e24500f6f75cc4c4fd375d92e3bd0e75edd3563aa819c6' 
  AND token = 'QDRhr5zM/wMl3xub1KAoQFGCDe5wd4VbXH7qZmnTAI4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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