SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd817239c34e5b1c4c42790d7d843b2d62b316612538b6211d30b49769bd51c2f' 
  AND token = 'dxXITamVCGxPQVxlSqBwBwat/E7nRNS/wjhGOEz+OhI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00015

JSON explain

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