SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '403b35ab55b30949400e2d2cbed086ba5dd3ca997316163dffb303835949be98' 
  AND token = 'M6QRyOugGH56lqwUnFaaRulfDSoFbrORSeBZeuNOqiA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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