SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a4c34954a50194e3290a47c3ea66a7c863d52c48fcbb847641d607302c639bf5' 
  AND token = 'OaJxaMXroU1ZFdIVmgBIy1e6jBCr3r3kq9YUrQRX2cY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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