SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'be3cefca747c3a0fda9dd72e0550c5082469282171d28eedd6a246b977b7620f' 
  AND token = 'BhyKOVJ+cn8ezugrItmznniMrKlo/WjXUEFDDU3tHmw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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