SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '12d8a89e7bed46ccd605ce494928c8aa46d74c3d446326f71442ab8389e0b609' 
  AND token = 'VuFsIbFzBaE6cm/Rd3UmhuGerVu/xmemCJhntO0cA9g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00057

JSON explain

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