SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1e755c2c7cbffcc2c6d3efa4cd9a2f24eeda083fcb93e03849891c9a1568e326' 
  AND token = 'vapI8c2ibJwy9EWtxp+eZv4uNJNBaRICZmRZjeNIO7Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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