SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0f15c3c9fb8a78b373f244c4f1988709efa2eb61675e37db7595413952cd6931' 
  AND token = 'iyCSdsD//e8dhQC0lGWYpywQhnsIx5Q8WvZD/IpAGhs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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