SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '516fccd52a5b5760a66ffb90a5dc68fcbe71001b22bf7a26dd8083476e1f0801' 
  AND token = 'STY3lHvOCszcdU/c9V/Fka/plNxmBYaxSplnfgqWoxg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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