SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7fe1a664b8cb4bada32c146507ced936c63bc2402262de8bafed109db7f0d726' 
  AND token = 'CMt/xMf8XdwPDA8HP3i99AxLRW8sk+kVphAVigmuAEQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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