SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b6c9da77fccc9ffc147ed33469e29efb4bd1935360bdc6cc97c5f51b69f59cb9' 
  AND token = 'HnVgwoOSkfTTo4b2O6glTUbGo3wUTuV+8sWmjuPONUw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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