SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'deb9082bc3574980f8a6462de75566880ed4448e12266440fcf67e66dc403253' 
  AND token = 'cJ//HtXUT+LqOKu31/XAgxlwwHBVBdUqnO0vG1H35vc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00049

JSON explain

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