SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '983835223572eef977183f34be5b541922731c56a84ea13b476eec817aff326a' 
  AND token = '/tghOTceu8A9K5562dTRX6DxngCxzHcywPeeboCVJ5I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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