SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2a978673c595aea17bbf07c51c84b3421734aa2317a2b6b01183c759ef832838' 
  AND token = 'kFbZ7T476kNqUEfccj0cyN8nWZnIGXgnulWBuXtxDCY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00048

JSON explain

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