SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7bc41e3d778226632f66815f350f6998891cef3cb1d3d2e1a9b8dbcd9fe6e122' 
  AND token = '6DogF2jLSwlIU5QhodIaoUv7zqDWgY8kEsx9I9+GlHk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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