SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '71d61152b4b557fd62667e7d72ee0cab26d9b9a6fff1a79760f22d6637171689' 
  AND token = 'TzFkmIMIgYI/IcZNjd+OGyE0/pfOXSiYKgF+W7SeMYA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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