SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6d23bcbfeb267be6b917320c90a97a2cc5bb0bfdd3b2e5a13023ece7c1823028' 
  AND token = 'A6PRwmAEL2XeImetvGBHiGOPifcVu2xtMTvz452MmE0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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