SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'a9f5e9ba98a91551eefc5d6111fc77f945ddc853cdb2cf0c675bfde37253860d' 
  AND token = '0Mpsxa4Re69/jZMAyN+/KzZYRgY4Z8hKqrni52ok+6c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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