SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a80be25838e0c54a3d935831bac15f8f57c8f3fa0f3d09f7cb4b1376bb077a45' 
  AND token = 'RR96tbpdtAQNRqZ+YtMikban7YEuYAjjdohtvp7xjEQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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