SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '468ec5e4943d589bf879d43e2aaa4a568e0bd569719cd59b490afc4382514050' 
  AND token = 'nEGPOZxSReIEAjiy0hmpUByn1awbnfkSOjh7YUzPlOc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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