SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'b21087eb4ccb20bf6e8fb883d098329176fb235965213931cf8e78b763b6cdc4' 
  AND token = '0vTXnpmUII5XQc5kF5fbMVoSC1hL+OxONq5dNjVz+Z8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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