SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '439a76b175158273a9e13e17554fabbbe6fb207660a058bc197994f3f78432ab' 
  AND token = 'lhRGLfhJiJ6QasXYFxO2+slKxG0vSP0AnaLQFrM+mgo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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