SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fff98f41d18f60f31a18707f9dd8f1c4bfd438451c5bf2f48bc75625616a75e2' 
  AND token = 'q2+kUsUjVrKZorw+vSVfNPJ3KLI5+KlbxnyMGqqFiXM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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