SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '21ccfa5f1804228f07143c310e75b75820bc40a999e4869f1390e72d5eb50666' 
  AND token = 'CWqP75WKfsnGZSGSDxEz4MLAv37VB9iWXfmLdO9OUhQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00073

JSON explain

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