SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5748bc4f696a43710d0cd5c1f5b3037116e7397c40305da31cffd971caf638ea' 
  AND token = 'v0JiWP7Wtf8ZxANXxwguGCAWZ/BgNgXDs4mKF2/gC10=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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