SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '55a6f0d4d38922fffd74e0e8d4f39ceedde500e99a88d22274e12881209acc20' 
  AND token = 'qHzqZH0xMlrO7pLW1erac3rcGiqmk+Js+X0tZmBq9Y0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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