SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '760579a09742f8455bc80d6c649260c446a6568e294739560d0775214944d152' 
  AND token = 'fRgqfqAOiZ/3p5PuZnpcRyVTnDNgauO4YL181VV9GTw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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