SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '334d3420eebbb447d4961253599526d490fbe05fe86f794bf7ac212b45cdc68b' 
  AND token = '6n9EcQS7f+WQfPrb9BkBKEGdiu98wFBYeTYlX9nZTno=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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