SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '91b6a043c8890ed6aacf4d2a034e530fe213cea79579074b378afc449067e393' 
  AND token = 'n0LnALFf2XlYbGJpQG5r6f3/MnIuY/5OiQ+gD7ajdgo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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