SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3838a9d734b923d61390c71744333d56455d192e21260fb4ecf8ea79ca3132c3' 
  AND token = 'XZ4+Qu/MRZImwYmyjJ7o5BCn6qRYRrtlVGirExWSo6Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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