SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '15bc3332ee0263cd8785318fabdb3b2c925f842e729bc3e978a745f4a50d5be7' 
  AND token = 'y7OsOlSCUJSsZMWYO798qeAcpRrlS2EwiyrGCK3bQis=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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