SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '716ed870775831727fb1c0f9ec6ecd21fbf648c260ed230637f7b8ea644ce6f6' 
  AND token = 'OgC3mf/fu4TljP0fzqRf7/UY43LpwNzonWpwvsUpRgo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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