SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'ea833bffd96b8b19dd44aa413c2df3b0696e18c1c9c7da64b1edd4e8603bd333' 
  AND token = 'vwnG+UOsisg+rJgPnvRQ2XV3Gv8vmjAcfGMl/WYQLZo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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