SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '754db25ef570d0ce72ccf604d21526efaad6f6bb01d038ecec0c67aa25821ac7' 
  AND token = 'xnhvFBVZI47srieKqxPYZL4hbO4IbmskhJCjhzu4FKQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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