SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4c2f73426e8f80bd51028ab51263638a585cd75b9a2ed343b65da40ab5613f4c' 
  AND token = 'bRKnmDCOaUoyk+VVayUckoRKDwUTB27YJh405L7adTw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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