SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '46a8acfdaa4bb866585035f903f3326b9a72035d9815203462b62a5a1218dc1d' 
  AND token = 'BG4P7Mv+XC4oHBDjGPtaxuP9mXJSH7yFQsRWL/b4Evo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}