SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '720f2fa3e4ce8ad30711a932518858b954494a369c347274891af739b0cff05f' 
  AND token = 'Wgqcai19d7trSk2gMS9arxHcuiJz70DOVDIIbbtAJYA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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