SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c86dbdd4780939f211e81e15b83549a20b5f27451dd3b5aacb2d126caa1e9a42' 
  AND token = 'jqTxw1K8IMFWlVE6xSdjHPx40PZi6P6YCxvu5SPCzic=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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