SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '30942820f3b5e801d313387a04d949d2eff8aeccedbe7f5a433cc7a01b78c160' 
  AND token = '6vmRblSKfpixIlQGBS7zwOSoqUxJM2+pdb6vWlDFbms=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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