SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f21bdeed8227c7a79581e41d773c3f479541d03f611fcce3f56a1138819b674e' 
  AND token = 'o3R/XgV7XlhRNsH8g3vJwn9ymBQfmMHw2OhxLwgoKkU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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