SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f82b9d8c3ec8386cd2bc5aba995ea944f0d8a028147f55fe35b303ee31a85f15' 
  AND token = 'LyJjfzQUpOF6sPdlwK7nzdVxuRqkN9c1lCgay+F/DFI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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