SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd8ba9bf416cb253ea2685795ad48de57c377053fd359d681ab874d4230f4f637' 
  AND token = '8cK5SfqESeXFYvPbzerhQhq+So17H6GbiW+O8+BtXqs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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