SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '94c3189795cc900cb2ed0ad86cf36539feecfed43bb6250da0155e003949f785' 
  AND token = 'hkwkKlcHzR6djwIt97XthuOqIJOkMcEsZDTU2DWmkng=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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