SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = 'c6e527cc66d37d2e7961417e64f417f3f7965733d9d47a97a59840a940347567' 
  AND token = 'cSqp75QJYixy/TgbiyxBWwgn1Zc84uCzSmyCr8uhVwU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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