SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9736395b864add92fe82795917cea36802284afc002d24879e5e641353805586' 
  AND token = 'TPVIvmb7eQdYvcsVruqVvmppLlTxzjsy6IOAvc5xbeM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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