SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e8bb9f3c7cadea9d8effd42111090457ec852c2ebc5afd00accd0e335ea23cbd' 
  AND token = '3sukYkiT2NXhBn6keEis2eM+XmzUXuhJp2kPebXicBk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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