SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ad28918e2b4ebb14c9548bcfb4346f3b5ab707aafd0aa477a1962ed8a435f590' 
  AND token = 'jaXwtIR9xCssqrAOFoKJs0yrwdIxGPMp3F0ZxEp1e0w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00055

JSON explain

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