SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '1c3ff861a1e916aef5af2d3602c699b9a2522f5bab6e160f73cd44eadbb14a87' 
  AND token = 'RLUd3p2SBxsPzV1hysSFN4DSQKK7qFiqlJuFDke65Vg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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