SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1eeb74db6ab972d2b3416ad906d20d44a1b479bed8f1f36aabc231b1934f2c8a' 
  AND token = 'LrB6nQMotgo1nVylTUDuRjI+cGXrdZPHaYcUOFaicBE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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