SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c532306360733949bb6f3de1082fdcdf4f582b3476d6e626d5c9b3894ce321f0' 
  AND token = 'Nj4O2aKlgpQ7EY/+DTMwKlwDwYUG1HZGnFXVaaZoHqg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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