SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '65397f2515b691f739d02925cab40c8d624fa8ed317668e209d3246a9c0fa314' 
  AND token = 'i8I9kGqLZs70udI19PmKWduLxTjuvoKfhPoJfNx/phk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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