SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '59d6e563f6c286bfc4415d8b90333168d24ef076add1eb46949b62546274476f' 
  AND token = 'P/7dwf1+wf/cKbZLvmmxMq4DTp+mOeeMWNfOWMgJYBY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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