SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '27b1e7d557ab7fdf43d86c3a76301a5c92a59c3c1e4f756a4c7152689303fca0' 
  AND token = 'l1W6dt6T5sJSuC87GaFfcjBKU0Htar84nlvUdM37fmc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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