SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'fb89863ea602f12cadad02c1c964ec403c090678a2289175e3bd5199aa954b76' 
  AND token = 'YPTJyOTya0Uddnnk1pstEEwce99LNIcmYka8ehdTk4k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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