SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '892df3af9c53edb4263ea57bd2713913ff604ee3a3a1e49a1ba5fc339f2f30d1' 
  AND token = 'JHmk+Uvj6TiTRKsSWKLnCqnnYUp0hg+Xxc1kGnFcPWc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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