SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '104638082a722fded4beae66e786e72f7b11fe087d73324d6a4b0b9a1a253bd2' 
  AND token = 'HoBfyD0zbn+DyeJyAQup5ZBi+e2ab3m7pT143NKQvXs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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