SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b42fc3a2d429508e9ace5af78254525a03411599fb069d99b575e508e31703a6' 
  AND token = 'KcSwOFQQbwKUboo+poBYrFu95vKec0ZVbTKy45Zclzw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00015

JSON explain

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