SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '293682921c296c2d260ab573fa322119ea60d576e81a2d7f59eb58c782584f2d' 
  AND token = '7r/Yc+mBTX/AZPlJ7h3uZXrYNYKhKx3frGB1LwZ8Gdg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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