SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '40781b82b2832fd6dbf0a65af5ce16f6631ddacd804c91421bd47852be519430' 
  AND token = 'uWpkwHbrxI1U8gc1EXEaRNYh6LtUpFxyqhX2ZVOgbBM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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