SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3f7716ebb853e687b430eaf26a1858524e42b5f0f228653649a1a8611b2e3896' 
  AND token = 'nJpYvfyQBSZjYSVx29+QgCOYoa+hoT3+LLb8spGWCBY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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