SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8effa72b7e31632ffcf657135dddfdfd22ab40cc0d29d36a9030bba085c64281' 
  AND token = 'znEfz2tgwrurknGrc+pcosFij59p1LPu2wOQXqyK+ns=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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