SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6cd02d9258b0f65c877d9fb5297cf86ed520511cbc54782aa0888b127f1c8b91' 
  AND token = 'pYagfbmjCDxMMXIwjn1LZXtiA2dVEhK16WMMdDvKWIk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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