SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f9c9e23f59386ba7d487b5a22eff3c2008c2ae12f7dd900d3d8508707955f968' 
  AND token = 'sTkRAOLTbXYLjSWN/4vzJOmo31Ztw5TsrQhTfo+LZGw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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