SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8d527a1f2f7bfb6c28d8b9f586e9970df8b002b117df3eb6f326ac0d15b822da' 
  AND token = 'nUTalN0rUOQlPzxyQG1PvPKuqwCcOda83+PTEVvffk4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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