SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5497912920b244a947e2d07c6dbc285e186d7ccd5419b0fe1a6b68f270a54c86' 
  AND token = '+N+RkGlwh/t3RI1/K3gZ6fjqHmJoyNAZeNg3+1PbfeA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}