SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = 'c57c1b6f6cbe7145b62bcde85667a4c59c34a87cfd23b39eff4423d50997a396' 
  AND token = 'HInzf3W+nsBGLE97/0ZCphCJqgy7GxqMNoWjjRcIGRs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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