SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e522ec7fa65f13eb0eb399f6e8fb8380edcf9cc618879b15f86966ffb3a352ec' 
  AND token = 'mkBDj3PIpTmKaapmhjQ5WKyBxlpbhjKC6umZnjGkcuo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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