SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '4c981ff6168eec3c3482e514067a73a0be0d8e4b8022c28121ae2a8cc5db4308' 
  AND token = '2duUHEWWDKISs/Yh69NzHgxTxdNd/FxihCahxd39lag=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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