SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'f289da965ccbf1db58a41b8453c386b6d093e516d1bff1b669766b9e4c235d06' 
  AND token = 'AvWwkKppszl2kcfN3D4WOk+huRn9M5eOomdOZY31G6A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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