SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '68b37adc07d481449224f704a93cabe018d5deeb4ea835a4b277b28a1868977c' 
  AND token = 'T4zkVUHXtVQ8LS+AVlO5WngSeyZBWCjpiyH3HDZPasQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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