SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f326bef6ba22a0467299a767a23b4c77871ee9d7d4cf16b280b06d6431dad554' 
  AND token = 'qlZoHkLvbbNTD62vKJnhCpvWf39Bd6LxKOrnBhyG45I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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