SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cb33e14fd102dc27673fd43a71c6316f8142c0ee1383daf2aa0dedb53abf5506' 
  AND token = '3xvQEMmiYqcdQOBZWAolQmlR6PvE7CKbqHa5l5wOL0g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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