SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9273dd50c69fe27de75dec54291221c88b9416fc260b3b02366c724088f61014' 
  AND token = 'q/JozDcuVj7AFEFDDhu0IvceUJGM+ZWzmXb6K4H5Ock=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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