SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3de145a134c7fd0088216b3b5573fe641998e7a9262de16da9a208531d0ab821' 
  AND token = 'ERb+N0/L/jgCeVYG+4faJxXIG5C5FNqu6sv1MusuX2Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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