SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6f8b4d42f26cc1497d159004bd3c9cd38498d88c98af621abddf7f02264e1a95' 
  AND token = 'Hc73Kl5AdfiqxpgNluHvUJMQwTFajogwkJipkE3GvTQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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