SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '52eede79b2354c33e3595482ddb8768a9af2f80f3eb0683d1de8462062a7a4a2' 
  AND token = 'wD7oRRNQ9mZ/ajDaYGuxtHPUnQSW0JxK9k2PxbtOiCQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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