SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3fd011353249189d5e7a666bfc72f45b0b07c93f03f4c509b73abae62e5d2825' 
  AND token = 'j29/d/OU2ZLNTpbLO64vlpWiGs5Qk8+IBzGHFdsBKVc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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