SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cb780e8efe96831aad496b50ea236ca2219f42e06f9a4705e7312cc998fd581b' 
  AND token = 'VhlCnYK56ae056LhzDO7lBJAYSmykhbbqXdlcKI2TK4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00046

JSON explain

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