SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dc77a5943c5df177dcfdbc21f7bb4d2458f2a4f67ce6e1147d80990d3f44fb8b' 
  AND token = 'xwmEvKA8MigG1BYGTHDTLsCCJ6hYlhDQdRFlnHPnhk0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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