SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'be9629246e21dd51e3c8ab435741fcc3897cff2e7d31498565f735019d9f16bf' 
  AND token = 'WzV4crI0d9utRbT0Qs4z6SXWafTps33X/FNCxUMtMLc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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