SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a01cb0c8aac2bfed024638e1207227e56a4513562571b56682553cc23c400bab' 
  AND token = 'MVKR5cbQ3oHMrp1c9I1TnKSPhz5PH/+W9WWvVTc7QAQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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