SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '100619280277b9cce489386714d1e1c454d5e0c4dd348e66fad09e78c5646472' 
  AND token = 'ClbtOrLhOKp9V18ViRNjk32F1tbikBXrbJ5nE/y9DR8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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