SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '76cef31a3eadd14d5bcd080c1a0e7ab3c9683eafad385f6ed96034d4cb175bc6' 
  AND token = 'bd2r63RoQDiFiz9DMY9x9aWnyrM0TtXVz8Wr1sSYMwU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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