SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '16eaa9dd2384c1dcef66748a78b716aa7baf00640e11720a71eac051c3aa1ede' 
  AND token = 'mr5xTeS2NXeNhA9CPO9mLXH6hjaPlxzgT8swMmrK8cw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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