SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'baa51b28ace800c8d8be7253e3d18fa22056b7c27f79812d6868f18365c3a860' 
  AND token = 'IWD7W9PYvCX7mURLHvV+GAsTp3/1z8G2+54q7OPhElg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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