SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '781840b6e49e1f3acc517c8d248268b4d989c408c04eb5b2e9878b8ee4771fd0' 
  AND token = '7KzeHYGYGUVDaI0vYOqU+kR3kx6wVIX9qG4TOBjhazE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00058

JSON explain

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