SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8118b18cf912f0f54740cca71d82e64003e09e5bed07ae2226546e943e66afd7' 
  AND token = '+zwj+bVIX6nJa9vRzesgYzuB9uruvQSvD7TNSiSUtJM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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