SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1548181a54ccd46af57e8103870e6d34f0737937506e5be65bc064ae4fd7dfce' 
  AND token = '/jcTPK9eO7qVb1eRu8rTXLbPaqqB0RmyMcx0/cuTj6o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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