SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c3d23059bc2e88cf8d65f832a5c3e4aaf016209f9937d59e308acd6b9b5697ff' 
  AND token = 'LoFX2n6PEpSQcYB7gQ/ejTwM8MQa0OO/xfj9aUfHLi4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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