SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9bc1feea0b68b7f5a8194802cb84e4bad037225ee100eefb747d904880c8fcf5' 
  AND token = '/mIEe0u+pTfw8kvBBOWidekdY8XunY5UUJle0VgszyM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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