SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '42796548b549096c4dcd074dc54480fd71a42b225618dd835eea2648c3507617' 
  AND token = 'b/Cu+VJxct6bBYWUJg2JwkMAIRlZJXR4O8W4CepyP7M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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