SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9c8d7a69af0b7e4bfc02eb826670591b367a0b113453dee04bdccd65169b7fd4' 
  AND token = 'QbGlsVxdQFmv/Dq6v+3p0MsPawFZW5dpOTzY/Fmj7N4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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