SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '592ba1adddbaf79e65ed3c8ce5e57d61592f935233dac6bd2f0e81239229d272' 
  AND token = '9p3K1Hy/GQOM6htL7WEiq//i9R/uRnHxLHK7c8pnAXs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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