SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd54d69d59132251c0d6da027b24977dd003720d949ecd4d26165aaec3d70fd5a' 
  AND token = 'gukOwKFEtbqZ+Md7xZ9+/pQUTBaZaPBbemEeGRkOWLc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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