SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dc2486436c4a409443cc80cefa232384d8ce86c0cb43f3f9540016750c757ead' 
  AND token = 'y9tiIhtFAzu48+IBHdJTWhCbf4UncSiOhbbE0kvrr98=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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