SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '53be43263c6ea99d87a99d73a58bde6f94c10294843acb4f7f6a8ad93a8e4871' 
  AND token = 'KwIVyEjDBHcYyqrTpwQVuG2I/p1ZuuxiuTSmZfNxejM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}