SELECT 
  1 
FROM 
  tmall_lock_keys 
WHERE 
  key_id = '6b02f003e2b2ea839e62fff457671992b97e5f12e9d5db6e6b2f0507b0b40b50' 
  AND token = 'IEw4GiBqF8EsWez+v7zVaeC5zd9YoqS24AZUSm47EyA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00745

JSON explain

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