SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'd9967de7febab4bd50cb51c1772ddc070f386b99d420a384ca0e45eed838019a' 
  AND token = 'unCKjbRWnjyLk1hWsHt/U+ozizlf5PISZxpTWIP+BaM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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