SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7e8a356fa533674ac50ae388a589107be47682d368dd4f56f894e27427893d1b' 
  AND token = 'Z3ozonaujMnymXkDlM5JtEgWLG4cnTw5CGVQIh/bKX4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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