SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '4021734d0716c5e0a1b8ed8951d1b0d5fff29408ccf007e031b0447689669b53' 
  AND token = 'VXeZzKdFL714bd9TZkhvnr4xmpwTq0hTYvTT3M3qa6E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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