SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9c1efd3a7ddd1f20c94231468a78b25e3fb0bb988baa06abd4deddc9b98d8dd6' 
  AND token = 'bermCnFcOYZBwYqzRYjGjPGY+Wz+yt8PNcaesc9+7GQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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