SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a85508610381db05275ea22385b88df29a6c54877b7c37c2a6e4af9447038ba8' 
  AND token = 'FwNTiPyGTLMOGHyr2dz52C/owRDTsUb0pBzhPKiqYVE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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