SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a23a9251294d2f1388efffcd8fa6747ac5238b55189bf799646441f2928f66f0' 
  AND token = 'vfzT3fBVBeUqml+VVAFhhguK0HV9rztKRDAdHWKOL7c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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