SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8e9c7f8a201cb841fd3144f4e85eacc21067fd07f3635dd3f41f95a971e3bdfd' 
  AND token = 'o8v/NHgM4Xm1xv4CnSXacGB6V0nsB7tTFOqBhJJIY3k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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