SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e34c02efb8b15d100dffd497cb4c330de1d04899e051d17c9690cb084280fcf1' 
  AND token = 'hsMOCN8RRerMtc6fyViRey6UMvXQwhGpGOsSJv3lRZs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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