SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '21305cd93500959d9312319ed16ec7511e35fcaa73fe24a93fe2e96e70b93a15' 
  AND token = 'Q3ZAjjySvjp01cf5XFYtYyaoWSdSt2jJDcIF+Ey76IY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00054

JSON explain

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