SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a371de2bb0debe70a61f22eb5224b81f26828789cad1c6bfbef955c009a453dd' 
  AND token = 'p4ru950mlue2zDRjzMcZRkW+crQyDbiF1LFjteGNFBo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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