SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c3d6ecc82faa23f90ecc42a8f642c44341287d13ea741cadaa46546a1352be9e' 
  AND token = '9I3IGRmGBYdKXPruI/Z5MBACLsNyGHFMWCOBhj+tYJM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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