SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a19f3f4f104925c65572d7bbef995de17ee557a285902a7808c046e9af9bf7ab' 
  AND token = 'guBLhrIT3+E9dcZcMXf40JPrQI05OyrTvyGifovPLV4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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