SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '291542c244d4915c903b3e1d6c6bd01a967a5bf1dc2de4d504f0253ef2cb16a5' 
  AND token = 'ErqAUAkxXETKuLguvxvqO56pCVF3artDCk8Og0FRi5c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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