SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f665ba31e22b003fd96d3b90512a5cddeebdd63accfa14f10421caa68c43d509' 
  AND token = '/EwDAHe6PkATWGgKpb+fh2r+z05j9STYlO2xgUHhL/A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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