SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0477cd9fb3906580e3349668492e8bede48f958b4db24c057c45ec5256183371' 
  AND token = '8BXKUCBlgpTtPVbno+irXDmb+tU/gBLRvhL9RKQoRV4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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