SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '15fc7ba1cf09e209507fc9576b88922033390e737778a8cdddc7bf469635bafc' 
  AND token = '3ewRSlIIrCQ3735HhCBx9TD+yMofYQe5hGHrgZ4QMaY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00046

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}