SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '517e3d93404851533883f3381f0bfb35546215431d9f1844eb6e55af08c3b92f' 
  AND token = 'pf5t6T3WTQPRuY7x5nM2TcDWs/y0eZ+0H3j6ahMrgMI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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