SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c5ab62e7f591fefcdbc1689a83da501a7a2b845d14c9c35fd9f9b54cd8fb1002' 
  AND token = 'KPYzdHqVyn17IoflXwzw9Xk5DAgZHov3Nwnf9nJGAvQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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