SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd3cfb1840455a106af8d558346fc05e94eb2bdb30b230af6712ff8c9c4a1a346' 
  AND token = 'ZkjYgqzeDDlz6OogoztVnS555Vj+QmQYLn7KMzvOEQY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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