SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '4b057281732df4036d274c3d0d64a9e1ec3ff22e9bd8d238b0d0c89afabf4bc7' 
  AND token = 'XVbZ+yVtMmkBvByOZPNzjaQCbaYqDV1xakKe3mhIQWw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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