SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9856d1cfbd759c6289efe054909cc54bd921b1afa353cf5a7003247b54817815' 
  AND token = 'sRPJHtt0OdPNQOXBh/RpvzjBSRHof6TfjkhGCeyITiw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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