SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '308f0ebf9ec951d67ee8c9052a38ea0c4143422e7a6ee6116079bd7012f3706e' 
  AND token = 'dvgxb2GFViSHe2zFM6tb1VFjenDSSBIjFNntaw9LFMA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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