SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c833dbb77cb380c89f589e9456a4c62436a7d96e9adf0050bbe39cb973ee2688' 
  AND token = 'hImxA+ZVOVY0VNDh/ytro/sj2CWYxUQy2zgMMG31tBQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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