SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '69d857d0189e2c414b93e040e75bd89ce2588082810c170378e7e52c2b9b4453' 
  AND token = 'YxcZJYcKnH2CE/2ogtIZrqZE/knPrEuI5tas3sRsArA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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