SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '368ccf10f4354600da078b031059bd5863dc5b4063c6049f1ee561f5e8d27b2a' 
  AND token = 's1xPZawbD1QiZf8jrI1jz5+hYltozcdSCKHTNxC80P4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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