SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '56d3af8267f986aa8fb5a5e6c00223d32d0a1164bec9b73f5a121ffb97811d42' 
  AND token = 'tvFlmSnOz/9NtoGvDVgM9q7ChQJSQ5Lh734yPBTl3kk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00040

JSON explain

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