SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = 'b429bdc3f5eabf59aa8dc775de1369d3800329a17bc6cbad21c4331c94d10c5f' 
  AND token = 'rHUOIRC/f6WkLCkQNq9JLqvfP9gTbNuM8rDMh9qy3iE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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