SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3a437f0cd25ebff8cefd58551a5fdc7d07d84e931aa090f634b8d17eebbe3b52' 
  AND token = '9Tv6Bh8LAVNUazwz5xhW1XXkqcRLjQu6IGXas+yDX3U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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