SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ad616dced590b42ec507b8ada24403417716f59ab8089b1e035989a5620b1434' 
  AND token = 'ZA8Z1IUbF47i5ytKPrFknkNDXdZOZfLmgLrotm3cDYs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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