SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9a34dda3346a781444c18cdbd95d040a6b52b03f39b1c1b7649589e76b6fc6bf' 
  AND token = '/AsbsJoQUUlKjJwfKqWA54j4bG+VsiPNlPQv27gp8aA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00052

JSON explain

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