SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '90b69b6ae22626f3c4e7030a4a05e3da0068dc3ca53fdd056195de28494187a6' 
  AND token = 'JqNDChkYaqO6tmqbHMzC2hDEKBjnXFGZRaEj+mNjtrI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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