SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8361a3785dcb53b9c16c96f2e7e6226cc983c6761008aa79900b8189f875f88d' 
  AND token = 'S97dMtGmXBpSspTOWTY2usx1UtmWwPkeo3fTanSuB6M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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