SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '90eedd3a17649136405010c146a1d8fbbc222a558ac67698195365f7bb4c6daf' 
  AND token = 'drTHUg439CHXcv5rFBDhdMG+K47gyQ5s44YyjgSHlcA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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