SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dd2a8482fc37dfd6712f51636afa9c76f35421e948ab980c88ff8cb575a62565' 
  AND token = 'SZXnscd+GV50AaeWdVdcUc7VnWy6jd37d4/pgj2Wjn4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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