SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bf77905482f828cc8dd9a25178a49b683880c67f93a5f58c63845458279645c5' 
  AND token = 'gIMc6pFGyps+HrHvw9Mch9drXdnkuVnwe2cQyWh+fAM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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