SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'af8496ee3044b4e6e18bc3237cc8968794f3787692b11047f8f9404fd76fbda0' 
  AND token = '8qlxEl4XOG1hKuLU9Wyd7PzLG5aHa6k867FoEoidrVE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}