SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '35409a0a5952fe42a66bfd84063a3403d2d7c9606c60679fa2f516e5d104371e' 
  AND token = 'Twgid1HFnOWHaV8BboQd4gcqgCtyYZcuW3XEYYeWsPI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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