SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'e7b024afa9115858421f0acc0bd34332e9eafc3354760eb2af3295939e6156a2' 
  AND token = 'vKGTVNYWSYjcYbMVsbkLDfxZFxkVTzZB58cF+yjjDio=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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