SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5b9633df75f0fcfb365218297769eb7f962c5b0bc90e2cd363de5adee08cc276' 
  AND token = 'JCqITQawGrDA3/OG7csMlWqjoJdHF55wrgOxs+kEzeo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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