SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bc4faff96b7a23dedca48a93375aea78b891a9a34c4759734c9da19b2f4fa375' 
  AND token = 'Mmvdu9xwWtJR2WKObAANKlXYnVpU+TjJKD/CtgST060=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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