SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bffbf860d19bf11f115bfb6f9dcc76235d9f294826d58f757a5308f9396a061f' 
  AND token = 'rTwBDXUoHZZgxHsKDSaAvYfR3VlnehY3FRRx2/c6Gis=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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