SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '99321855998446ebf889476f3e2d31d5f8035405021363564903a47e78697abe' 
  AND token = 'sRVK1U4nQ5OrxOvln6zVsMLK4zHX0dq6jps3L5yRGyA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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