SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3721ce7e8844e2fbaee9b029e337e9ed72d7c7a7cf2ec903fffefd1624fc40dc' 
  AND token = 'uDSZhGF63NL2EVagggASZyTmM9Qwtj+0VuAdGCihOKw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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