SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '726026236e0d686c5fec26bfd1b63bbb09db41b0f92e9be7db1895ea6088ed2c' 
  AND token = 'Lnr65rUIS0WQS6YFg2tSC/02zRyUT4D4k6rG0s+YRjA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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