SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7b7884f21935a670c4d884f05cb48921ebd59cec45dba8bd3e50391a0748b578' 
  AND token = '6q0S9bMEs0Lku7Qvd9oVJGUc1DE2ujfUmZMYZGDlYrY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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