SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '8f8c03eb0628753d203f1d9fe7ba401fe71bf7649e6f142bbca301dbc8f1f3d3' 
  AND token = 'ON5+xs3+1rFvwaSSJvq34rp7F2AnnCWH6MyJdYhcwlU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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