SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '96c81974b704ba41fe08d617d17342345b96972e187c7e1d379558b95a25f3b6' 
  AND token = '+dpU0OGACCbz6U/kSVk9YjNeYYBM0EGKqKfx7U/msf8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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