SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8260710dad46bded4f7635133d3f3881aff295a82fa82dab1b62c290627361e4' 
  AND token = 'IDEllOrTJ+rWSMB3AKfItjryuCU7JMAyxqC45xZKKeg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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