SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '53a9e376d2ce8b0523af5b035ec42b0d49f2dc08e35cd6b93ea15076e15c8d91' 
  AND token = 'QBzvdRFGgSehs2fnD7KfZmcH73toCS0oakFtVVsneu0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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