SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fe357c5de40b5ddebbd9e23dc159081fb32be8d9fde43ed21e1ad1faee646b70' 
  AND token = 'MRJhSvRK0acNvJKlMMHB8qtFs+rVUXMvF1SfdgqYros=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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