SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ea12e48bced819bb84f5c788d92f0f9390f7b1e03f1a11560f309aad14e84e7c' 
  AND token = '4HhDERDgouqVZNfOiojWOZ/TW7qNLMHYQEkSQBjS+NA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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