SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '55f1d2195a2b75cefd57f00abb76954224d9c63933e01e23a9082b0f7cfc8a4a' 
  AND token = 'vS83yMmwM58Y3ohdw0PMtQrxIgKxibkjltVW7GqHaMY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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