SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6d838fed84294f156e9f5a481b04f266f5476bd26c4a5f3718928462e1f4d985' 
  AND token = 'CFXH+IDEHlWBs8MVzUk1VhRmvno8qxF8gFq6/lla4Nw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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