SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fc0612177d497725885b10062a812e62f0bc24f539f1a689327fa67d68b4f611' 
  AND token = 'A9mCR91dNiabPDhQMcm77TxqOCdUdyEZRuP/sElkdzQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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