SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c8de87190b8b14ea2d599bec5f3137b9c3adbfcd6fb2a1686e54e8cc50561700' 
  AND token = 'fXJEPd+vFBg0WejvzH29KuYu/VupEARJiQf3jyR26oM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00046

JSON explain

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