SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '411343393a205d3b57053171cb131a3fa8383b1f8a2b1111fe0c764941ebc592' 
  AND token = '8dHFKesumdE50W1JcNdaktyvDsvr7LyH68w2jnsgGZo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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