SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5468acaa08e9849a4155d5f5c020d617027975f1e8a1c8faf3a3fa58cb3860da' 
  AND token = '7qXB9MgTiaIGJrxhGMrMhUOE1VRZm8hlCa0xiEvy8n0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00055

JSON explain

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