SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '51a303eb1e072ffee26264596eee6e29edbdc4890a44da6903d951c0f402cecb' 
  AND token = 'SJKUC9Mo205Yqaa02mKluuRcaiOw8vJSrCZdjQWN7Do=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00051

JSON explain

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