SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '84fc2b5706648f78b286a27ba881148916549ecb9ffbdac284d0b98e5210d693' 
  AND token = 'vQq0LzoYJ4m1BMs8VDe3LNdj5m5OCEYj4hV+fy6vXmo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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