SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'df53d473b7f0c08c0790241552c80a5ce6948be07069e37679abd0321bb21d18' 
  AND token = 'MEgjdGo6KvYbcqGBfVjflRUMxGufKoDRKnIaHNvQcaE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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