SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'aac421a4354781570f6e7552ee5bef4f96224409d9c9297effb6ba5b896a23b6' 
  AND token = '9e/BwzFWuTzF2ZVIzA4UgoOG8+Sg/JLa+UK35nJ1J/Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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