SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'fa9ef9f20a1adff1e4487406f802b5b8e789fa7ad77eb5dab833b29dd8943b50' 
  AND token = 'a7IYJM2wPpghx9BR6VaFWX8lPH+PUqu0KzXap5xArS8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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