SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8fda70b3c87c6c4c5af3b85d0b0c3bf57926b3665ce2ab0890f9fa8fd6e0952e' 
  AND token = 'tXyBlCFZQZK9UD4mMEajAkVYyFj1rgoNJ9aq/TfNMgk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00057

JSON explain

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