SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b1fb76a1892ae71e5677ffb7554f07561f62c702aa5895133f0ff35be48d3dce' 
  AND token = '+uyRXtQlj3SrCKe+4vrN1YyoqjjU2D1zh4IrVQJMgnA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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