SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7bbac772f900b49e8346b7b8f0bce2dd91792a446f095dade066c875c2418db2' 
  AND token = 'uIJjJ2ZtTXeV3QJDgz/mmYt/BCqchYNKEhlGHdBSPi0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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