SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f237e8c28cb3c31aceee93f911487dd1f93c5fb4f120968d6436593f045f9936' 
  AND token = 'wpYpVWlnShlCQuoGbdMZcKJXB0g6kW6kO1o2KMOZE88=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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