SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '76ec1debec9e2ebddd81b016e2e802a27534f05a185902cb8d999fe8cc6204e6' 
  AND token = 'kJC88yJ7zDw5zDmRLw7GvA4pxeVhoroGs00HCoQP40w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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